This may be a bit tangential to your initial points, Peasant, but I provide music, as entertainment and as therapeutic recreation, for a wide array of senior communities (from alzheimer's units to nursing and rehab centers to independent living residences and drop-in senior centers). There are a lot of facilities around, both in Portland and in Seattle, and I find I can earn a living at it by having frequent clients in both cities.    But while I travel to Seattle to "gig," I find Seattle musicians coming to Portland to play here.    Even within cities, I know that I may be driving 30 miles across town to do a program on the west side while a west side entertainer is driving to my neck of the woods to do the same.

I would GLADLY knock $5 to $15 off my fee for 1-hour gigs if I could get the activity directors to help me avoid a lot of the travel time.   This could mean trying to hire mostly people who lived fairly close, or it could mean coordinating with the ADs of nearby facilities so we providers could do 2 to 4 gigs in the same area the same day. Also, if more ADs would schedule programs in the morning or early afternoon or after 6 PM -- or on weekends -- I could also lower my fees because I wouldn't so often get stuck in horrendous Friday afternoon or rush hour traffic. But I find most of the ADs either have never thought of this or just aren't willing to bend that way, even while they are complaining about their budget cuts.

So, in my case, YES, my sometimes-extensive travel does drive up my costs and thus what I need to charge.   

I considered joining the local musicians' union at one time, but their policies were that I had to charge at least $60 for a gig (back in the early '90s) -- even if it was a 30-min. gig 1 block from my house with no need for amps, etc.   OTOH, their rules would have allowed me to drive to the Oregon Coast and back for a 4-hour gig and still charge only $60.
This never made sense to me, as travel can easily take more time than the gig itself and cost a good chunk of whatever I'm being paid.   
Musicians could charge less and still have the same bottom line if they could get as many good gigs locally as they do on the road.