How common MV is, is regional. In some places with only HPS or LED, it is VERY rare. But, in some places that still have MV, it’s common.

I’ve been to cities full of mercury, I've been to places primarily lit by mercury vapor. I’ve seen cobra heads from the 2000s in MV (AEL 113, AEL 125, Cooper OVX, Cooper OVZ, GE M250, AEL 115, AEL 125, GE M400). They’re rare or nonexistent in most cities, but in some, they’re highly common. When I say “rare in mercury vapor” I mean it for most cities. However, in some cities (like Charleston, SC), they’re not rare at all. I believe I’ve seen the OVZ in MV (despite me saying they’re rare), but I’m only saying rare as in they’re not common in the U.S. just because they’re common in certain cities.

Toledo, OH had a lot of MV’s before going LED (I’ve been there before). My own city didn’t have much. Before going LED, they only had HPS.

Mercury vapor fixtures manufactured up into the 1980s are relatively common in many places. Mercury vapor was still very common in the 1980s, many cities didn't go HPS until the 90s or 2000s, but some went HPS as early as the 1970s.

How common mercury vapor is depends on the city and what power company they use (Duke Energy and Toledo Edison for example, used MV up until they were banned). Toledo now is all LED, but before they went LED, they had a lot of MV, and so did suburbs like Perrysburg and Sylvania.

The vast majority of places are now lit with either LED or HPS, but there are still some MV-dominate cities, and there are even certain cities lit primarily with MH.