For me, none of that. For me, it's the stress/worry about whether they're doing it right, what they're breaking, the mess they're making, etc. A succession of poor experiences means we actively avoid having tradespeople in to do stuff and do as much as we can ourselves, and check what they're doing the few times we have to have someone in.
I.e. a while ago, we had a useless gas engineer install a new boiler. He showed us it appearing to work and then made a quick getaway. Within minutes of him leaving, it was showing error messages, which we managed to clear by following the instruction book, but then the hot water would cut out after 30 seconds or so with a different error message. He refused to come back, blocked our phone number, etc.
Got someone else in, and found the gas supply pipe pressure was too low which was causing it to cut out when working hard, i.e. providing hot water. He also pointed out the installation checklist hadn't been completed nor signed off. So we had to pay him to do it all again, during which he found the pipework wasn't fitted to the right places in the boiler, so he had to change that too!
When my MIL needed a new boiler a couple of months ago, I went to stay in with her during the two days the engineer was there. Obviously I couldn't check the detail of what he was connecting to where, but I knew enough to ask him to confirm he'd checked the gas supply pressure, and also to check he'd signed off the installation checklist and certificate. Also went round all the radiators with him, and had him stand next to me as I checked all the hot times produced boiling water for at least a couple of minutes each. In the event, all was good, as it's been no problem in the couple of months since installation. But experiencing the shoddy installation ourselves gave us enough knowledge to check MIL's engineer was doing things right.