I am wondering why there were never any quartz metal halide lamps and ceramic metal halide lamps that were used as drop-in retrofits for US low wattage HPS fixtures designed for HPS lamps with 52-55v arc tubes? In Europe, they used standard quartz metal halide lamps such as Venture’s Whitelux HIE line and ceramic metal halide lamps such as the CDO line from Philips as drop-in retrofits for low wattage HPS lamps over there.

It boils down to just 120V being the mains voltage in the US, vs around 230V in Europe.
The problem is the low arc voltage of the US low power HPS lamps and mainly their ballast OCV (that being just the 120V mains). It is not possible to design MHs to perform in any reasonable manner with compatible electrical specs.
Many contributors to the arc voltage drop are just fixed in absolute value (related to energy barriers among different materials), which do not luminate, just create a heat. Sodium has rather low energy barriers, so a low voltage arc is still usable.