Lots of places have their own HVAC techs in house, if they have enough HVAC work to justify it. Even if it's not their core line of business. They will do whatever costs less, +/- some amount of subjective "hassle factor."

Especially when it's "line critical" to their business, or if the person can do other things as well.

Larger hotels often have dedicated staff for things like HVAC, etc, because the importance of getting things fixed quick if possible is worth the cost of having someone onsite/available.

And you see similar things with colleges, etc; they often have a maintenance deportment that can be pretty large (though no doubt they've spun it off and brought it back in-house for the same "change is progress" reasons).

I have dealt with a large number of retail colo providers, wholesale data center providers and corporate owned data centers across the US over the last 20 years and all of them used contractors for HVAC and electrical. I'm not saying dedicated staff never happens but it is definitely not the norm.