If I understand this right, basically they are banned because they are not as efficient a light source as others. I can think of one exampl of an in-efficient light source not being touched. For example, a 175 watt MV lamp puts out light about equal to a 300 watt halogen lamp and has an average life of 24000 hours, halogen about 2000. Even if you got about half the life of the MV lamp with usable light, it would still be more efficient and last longer than the halogen, saving energy/money. Is that right?

That's right, but unless you connect MV behavior with human factor. Simply MV's fell "victim" of their own reliability:
Most lamp on the end of their life or die completely and/or start to behave annoyingly (burner explosion, cycling, color changes, do not strike,...), what ensure responsible people take care to relamp. Failure to do so yield or to nonworking fixture, what (if properly designed) does not consume power, or strong user complaints (when cycling).
In contrast MV's only gradually glow dimmer, so slowly, it is not noticed by anybody, while still drawing full power. The point, where the lamp output fall below some threshold (in recent years industry chooses 70% as an economic brake-trough), is then defined as lamp's end of life, so when lamp should be replaced.
The fact the loss of brightness is so slow mean, the user should set and follow relamping schedule. On the other side the high percentage of working lamps at this "age" mean, such relamping might be limited to ONLY scheduled slots, e.g. in the scope of trough site maintenance.
But because people are people (and not machines), such replacement of "still working" bulbs is often considered as a luxury, so an operating cost, what might be postponed.
The result is then low efficacy lamp (with double the rated lifetime or often more burnt age), what really consumes power and does not provide much light...

What is really irony here, today's "green flagship", LED, has the same habit: Never totally burn out, but gradually, trough it's life, loose efficacy. So my guess, they would be accused of low efficacy in the exactly the same way as MV's, unless their ballast would incorporate something like "End of life low efficacy cutout" shutting them completely down...

It just sucks. There are many other less efficient light sources that should be gone after before they ever went after MV.

I was also looking at the DarkSky site and it seems to me they are a bunch of loons. Sure you can cut down light pollution but you cannot eliminate it after all, light does reflect off of other surfaces and reflect into the atmosphere.

I was also looking at the DarkSky site and it seems to me they are a bunch of loons. Sure you can cut down light pollution but you cannot eliminate it after all, light does reflect off of other surfaces and reflect into the atmosphere.

And it seems the "dark sky association" likes the nasty orange sodium cloud which lights up the whole sky more than a faint whitish glow from mercury lamps.

That's right.

When mercs where prevalent the city glow at night was noticable but only a little. Ever since HPS came into play, the 'orange cloud' over the city at night is very bright. It contradicts DSs name. How can you have a dark sky with the glow of HPS all over the place? I like HPS, I think it's a unique light source but getting rid of MV or banning any other light type is not the answer. Dark Sky is a bunch of loons. Around my neighborhood and in San Jose in general everything is lit by LPS, a very ugly-orange light source, at least those will get replaced by LED which are, guess what, white! So when all these LPS fixtures get replaced by LEDS the bright orange cloud over the city will be replaced by a white cloud so it will be even brighter! It doesn't matter what light source you use one of light's funny characteristics is it likes to reflect off of almost any surface so any light source is going to reflect into the night sky so this whole dark sky thing seems totally pointless.

DarkSky "protect" the sky only for astronomers (using equipment, so e.g. filters), but by far not for general public (having only naked eyes). Otherwise if they ban MV's, they should ban LPS at first, as due to LPS size it is unfeasible to make proper and at the same time efficient beam control.
Their first claims are to protect dark sky to be able to see stars, but few rows later they do not hesitate to say (loose "citation") "monochromatic yellow is not as an issue, as it might be easily filtered out" - what the heck this mean?