Customer service in general is the issue. Even the most reasonable, nice people can turn into jerks / children / whatever when they get hit with a bill or an outcome they don't like.
My father in law drills water wells. He literally has clients who balk at the cost of a new well compared to what a well cost back in the 70's or 80's. I made a point that he claims he will use the next time someone starts complaining like that. His service truck can haul around 400 gallons of fuel, of which he can use to run his drill for about 4 hours a day. Recently, he was spending nearly $2500 a day in fuel for one days worth of drilling. In the 80's, he would have spent about $300 on that fuel. The steel pipe used to line the well? About $32 a foot today, back then? Not even $5 a foot. And on, and on. Yeah your well is going to cost more than it would have 40 or 50 years ago.
Similarly, a client of his took the liberty of taking the part number off of a UV light he installed for bacterial treatment and popped it into the ole google. Found what he felt was "the same thing" and then called up outraged that he was charged $800 for the part plus installation when it was "only a $300" light. So my father in law asks him... so when this thing breaks, or needs some sort of work... are you going to call amazon or are you going to call me? And he asked, am I allowed to make any money for buying this part (which cost more than this $300 light your showing me) and coming over to your home and installing it for you? Or could you do the install yourself. Oh my lord....
It's 100% the reason I am not in business for myself. I just couldn't handle it.