I wonder why B22 bases were used for SOX, SOI/H, and SO/H lamps and not another special base dedicated for them. One issue I might notice with using B22 bases on these LPS lamps is that someone might install a British household bulb in the fixture and it might damage the ballast or the bulb itself.

I wonder why B22 bases were used for SOX, SOI/H, and SO/H lamps and not another special base dedicated for them. One issue I might notice with using B22 bases on these LPS lamps is that someone might install a British household bulb in the fixture and it might damage the ballast or the bulb itself.

Why not? For the bulb no one cares and the ballast is supposed to survive even a dying SOX, the incandescent can not be worse to it.

B22 bases allow the fixture manufacturer to control lamp positioning. With LPS lamps it is desirable to have the 2 tubes in a level plane within the fixture. Using a B22 ensures that the parallel discharge tubes will be in the optimal position as all LPS lamps have the tubes clocked/oriented to the base.

Also, think about where LPS fixtures are installed. The average Joe isn't going to be relamping these with a GLS lamp. Usually only a technician would be relamping the typical LPS fixture. I also highly doubt stuffing a GLS bulb into a LPS fixture would be a catastrophe.