Timely response, but expensive. I've been having a...

Timely response, but expensive. I've been having a few issues at a rental property lately, most of which they fixed. Most recently, however, I was charged $200 for the plumber to come out and tell me that my broken valve stem is old, corroded and will not budge. This much I knew from trying to remove it myself - but I guess you're paying for the expert opinion. Now I'm out $200 and the problem still very much exists. This poses a great question... what's the motivation to do a great job when you'll get paid just for trying?? BTW... I was told the $200 charge was because the plumber had to "access his tools" to diagnose the problem. As opposed to what, just staring at it to figure out what is going on?

In a pinch I might use Waterworks again, but not if I can help it.