I notice typically I've seen on here that with HPS lamps, the 400W and higher is generally the tubular shape, while the lower wattage is the elliptical. So I was looking on Google to see if tubular shape lamps of lower wattages exist. I saw some on here but most appear to be in European countries. I saw GE Lucalox and Osram. But not really in US. Why is that?

Because tubular lamps are more compact than elliptical lamps, even more compact than reduced size elliptical lamps. Tubular HPS lamps are available from 70-1000W.

Why the Europeans embraced tubular jacketed HID lamps, and North America adopted Elliptical, I am not sure, perhaps someone on here has an explanation.

However, some pros and cons to both ive noticed over my years of relamping jobs. Tubular shaped lamps are great for precision floodlighting and low-profile applications, the larger envelope of ED and BT shaped lamps are generally restricted to larger, bulkier fixtures where arc-tube proximity to the reflector doesnt matter much. But, lamp life and performance is almost always lower in Tubular shaped lamps when compared to their BT and ED counterparts. I cannot speak on the Tubular HPS lamps as I havent installed any, but can say, without a doubt that the T-shaped Metal Halide lamps do suffer from shorter life and faster lumen/spectrum depreciation than the Ellipticals.

Regarding the sensitivity to the outer shape, the MH are far different story than HPS. The main difference is the MH generate way more thermal load and that is the main factor in shorter life. The HPS run way cooler, so the tubular outer shape means not much life problems by its own.
And the reason for their higher popularity in Europe is their compactness - it fits to smaller fixtures.

The reason why the are not that common in the US could be related to the popularity of a CWA style ballast in 120V world, which can not offer that much thermal stabilization as the simple series choke could offer in the 230V environment. The tubular outer reflects quite some heat back at the arctube, leading to worse arc tube temperature so pressure control. As the CWA is inherently less thermally stable, it could be too bad for the tubular concept, so the benefit of the oval shapes became important.

I have some tubular style 600W HPS grow lamps.They are common with grow lights-600W.Allows for a smaller more compact fixture.

Because tubular lamps are more compact than elliptical lamps, even more compact than reduced size elliptical lamps. Tubular HPS lamps are available from 70-1000W.

I've seen a tubular 50W HPS before

I have some tubular style 600W HPS grow lamps.They are common with grow lights-600W.Allows for a smaller more compact fixture.

Is there something you want to tell us.??   

I've seen a tubular 50W HPS before

We have a few tubular 50W ones, here is a GE Lucalox XO lamp made in Hungary. These have the best colour of any of the HPS lamps in our opinion 

I forgot about the existence of the tubular 50W and even the tubular 35W HPS lamps. HPS lamps under 70W aren't exists in Israel.

Don't grow plants-have the bulbs and fixtures in my collection.Light them on occasions,too!

The US does use ET shape lamps in 250w+ to my knowledge. I have a set of 400w GE HPS that are ET shape.