Mercury vapor lamps are more energy efficient than incandescent and most fluorescent lights, with luminous efficacies of 35 to 65 lumens/watt.[1] Their other advantages are a long bulb lifetime in the range of 24,000 hours and a high intensity, clear white light output. For these reasons, they are used for large area overhead lighting, such as in factories, warehouses, and sports arenas as well as for streetlights.
Schiler, Marc (1997). Simplified Design of Building Lighting, 4th Ed. USA: John Wiley and Sons. p. 27. ISBN 0-471-19210-4.
The fact that the government is banning MV lamps really grinds my gears. New T8 lighting and LEDs don't last nearly as long, and end up putting more wastes in landfills than an MV lamp, which is easily recycled. Also, the ballasts of MV lamps have proven to stand up to the test of time, withstanding high heat and humidity, while CFLs will cook in high heat or corrode and be rendered useless by humidity. Also, T8 IS ballasts will sometimes fail early, producing a smoke show and an ungodly high pitched noise that is unpleasant to experience.

Direct compare of MV vs fluorescents does not make much sense, it is like comparing a race car with a damper truck, both are vehicles using an MW-range engine to move on the ground (the same statement as both fluorescents, as well as MV emit light), but each holds stronger in totally different field.

The 30..50lm/W is the efficacy of really small fluorescent lamps, usually 400lm and below, while the 50..60lm/W is the efficacy of MV's of 10000lm and above. When comparing similar lumen packages, you end up with barely 3200lm (average over life) of an 80W MV, with about 6000lm of a pair of F36T8, both consuming about the same 90W from the mains...

There is not much question about why the bans are here - politicians just have to "show off" they are doing something "for the public", that is all. The lighting companies, willing to kill the not that profitable markets, just gave to the politicians an opportunity.

What brings MV's to the front positions on the "ban" list is their reliability (they very rarely abruptly stop working) and a false economy in peoples reasoning - "It still lights, so why to replace it". That behavior had really caused the MV systems becoming nearly as inefficient as the incandescents - so good "reason" to be one of the first on the ban list.
Other systems just start to cycle or completely stop working, so really force the user to replace the lamp, MV just gradually dims down, so the ONLY reason for lamp replacement is the low efficacy and output of the old one.
Technically the MV should not be that bad, when maintained well (lamps replaced in time,...), it allows the maintenance to be really cheap (no unplanned work,...). But all that expect the people would behave strictly rationally and really always take into account all available facts.

Ideally, mercs would not be in the process of banishment, but that's just technological evolution. It's a shame to see, really. 

The problem is, the electricity generation is without any doubt harming our environment, so politicians are forced to "do something".
At the same time lighting companies are seeing loosing profit on older technology products, as the competition is pressing the sale prices, so they want to get rid of that business. But doing so on their own would be perceived badly by their customers (that company is not supporting all range, so let's go "next door", where I could have everything in one place).
Third piece of that puzzle is the mentality of "Why to scrap still working lamp", leading to way too much overaged lamps in the field, which when counted into the average efficacy leads to the average efficacy almost equivalent to the incandescents.
When mixed together, the lamp makers spot the opportunity to get rid of the not that profitable business withot creating the bad impression of "not supporting everything", the politicians spot an opportunity to show off "they are doing good things for the environment" and the result was the lamp bans.

You prove a strong point, Medved. Now with manufacturers skimping on Hg and crappily building fluorescents, they are most likely next up to go extinct due to LEDisease.

Well, I don't think so. The strong classical lighting makers quite slept over the first boom of LED's, so other companies start pushing them out.

The problem is, with the LED's the main money come from the semiconductor manufacture, but that was, where the originally electronic semiconductor companies became way ahead (strong knowledge base, semiconductor foundries in full operation,...).
The "classical" lighting makers are either forced to buy the chips, or just the leftover, so those less profitable, semiconductor fabs.
It is the the fluorescents and high tech HID's (mainly CMH,...; where is not much competition) business, where the classical lighting makers have still quite reasonable profit, so I don't think they will hurry out of this that fast...
The thing is, these days the "classical" lighting business is not that attractive for the low cost companies (they are lacking the knowledge), they go rather directly for making the LED products (not the semiconductors alone, those they buy as input material, but the final product assembly - that is rather easy activity without any special technology requirements), so the competition within the fluorescent/HID business is not that strong anymore.

I like how stores go to great lengths promoting them and trying to spread LEDiseasr, but then I see them in the clearance aisle at Walmart for $5. I did buy, however, some LED spot lights by utilitech for the bathroom and basement last November and no failures have been reported yet.