How does your crew charge?

Question for producers out there.

When hiring crew, I'm finding more and more that they're nickle-and-diming me to death on the final invoices. Is this happening to you guys?

For example, my DIT charged me "rental" for his dolly which he used to wheel his DIT station from his car to the blackout tent on set. It was only $5 but really?

My gaffer charged me round-trip mileage and driving time from the set in the city to his house (which is a 2-hour commute to the country).

A couple of grips charged me an hour of overtime for sitting in traffic after they left the set.

I realize you have to draw a line somewhere and I'm trying to figure out where that line should be. I mean ideally I'd love to charge my clients for "thought time" while sitting on the toilet thinking about their project but it doesn't work that way. Unless you're an attorney or an ad agency.

Thoughts?