I wasn't happy either when most of the mercury vapor fixtures in my town were all replaced with high pressure sodium fixtures a few years ago. I saw a few mercury vapor fixtures around there that were only 1-2 years old basically just taken down and scrapped.
We haven't installed mercs since the late 80s- early 90's. The last mercury fixtures used were the 100w AE 113s. After that it was HPS 50 and 100w HPS 113s and M-250R2s.
The last merc installed around here for replacements is in April 2008....but the last BRAND NEW mercs installed was around 2002.....I know some merc posttops that was installed in 1998
I think it's because MH units are initially more expensive, the lamps cost more, and the lamps don't last as long (well, PSMH is pretty close) and overall cost more to maintain. All of the lights NGrid installs are drop lens, so DSA isn't a problem here thankfully.
100 watt mercury vapor streetlights don't exist in my area, there were only a few 100 watt mercury vapor streetlights in service in Indiana Township, PA until 2007. Metal halide lights are also only installed upon request.
The only MH lights here are acorn lights in Downtown Providence, which i believe are owned by RIDOT, but since NGrid is too stubborn to service MH lights, RIDOT probably has a private contractor repair them since i'm pretty sure NGrid is in charge of RIDOT's cobraheads.
I believe there are a few MH Cooper OVY on steel truss arms from RIDOT on the Newport bridge, but they're removed as the lamps fail (or when they finally service it after it's been out for awhile). Some might have mercury vapor lamps that were used to relamp them back when NGrid still relamped other wattage mercs. most of the lights are M-250R2, but there are a few HPS OVF, newer M-400, newer FCO M-400, AE 25, and M-400R2 as well.