It's probably just because Bitcoin ATMs don't require much upkeep.
You'd think so, but apparently they do. Most people don't give feedback on Coinatmradar, so they will still list them even if they haven't been working for years. In Spain one of the largest providers (ATMs Bitcoin Exchange SL) has turned into a big scam. Besides not refunding when they ATMs aren't paying what they should (which is very frequently), the owner is also running several ponzies which have stopped paying. There are several threads about it in the Spanish forum. I tried to warn about it on Coinatmradar but was banned.