That's funny, I was thinking the same thing. It has been a couple of years since I was out there, but I brought my TH-D72 with me a small mag mount. I took it with me on a walk down the strip and couldn't get a single digipeat. It wasn't until I took a drive to Hoover Dam that I finally got a hit about half way there. Coverage was very sparse.
I was in Las Vegas at the end of April 2016 for a ham convention. I had my TH-D72A HT and a mobile whip antenna on a trunk mount. I had no problems being picked up by digipeaters on the mountaintops around the Las Vegas Valley. Even on the Strip. The
http://aprs.fi web site picked me up as I drove around there.
An HT and normal/short duckie along the Strip might not work well with all of the tall buildings, but I didn't need to use an amplifier with my HT or consider buying a TM-D710G or a Yaesu APRS-ready mobile. That is a benefit for those of us out west - mountaintop digipeaters that cover large areas.
Compared to when I was out there almost a decade ago and APRS was booming. Byon had a TinyTrak in just about every ham's car out there and the map was filled.
Some of the change may be from the APRS-ready transceivers from Kenwood and - now - Yaesu. When the transceiver has the TNC (at least APRS functionality) and GPS in one box, it makes APRS a lot easier than in the past when you had to put 2 or 3 components (radio, TNC, GPS) together to run APRS.
I still see lots of APRS activity when I travel around Arizona, California, and southern Nevada. Many are using APRS for tracking vehicles or individuals on foot. I also see APRS activity on the orbiting digipeaters on the International Space Station and the NO-84 satellite. For the orbiting digipeaters, APRS messages are used to make exchanges for contacts, as well as transmitting our locations so we are seen across the country. I regularly use my Kenwood HTs (TH-D72A, TH-D74A) to work these digipeaters and make contacts. Activity from the orbiting digipeaters will make it onto
http://aprs.fi via gateway stations, as well as two other sites:
http://ariss.net/ (for ISS)
http://pcsat.aprs.org/ (for NO-84, and - if operational - NO-44)
73!