If anyone's interested, here is the website to the company on the vans. It seems they install security and fire alarm systems. It could be 5G, but you never know.

http://www.systemspluswi.com/

There aren't enough people in my area to warrant placing mm-wave 5G cells every block or so. We'll eventually get the long wave 4G-like version, which may be 20% faster than 4G, but handles more traffic. So, at least it'll be an improvement.