Our rule for leagues/tournaments around here has always been 'one pitch' - one pitch and we get paid a full fee. Of course, we tell our people not to abuse it. I remember only one time in 25 years, were the field was in horrible shape, the league wanted my partner and me to start it, and it started POURING again in the top of the 1st. Oh well...
In HS, our contract is very specific: any cancellation when we have shown up, and the game isn't played, and we get a $25 travel fee. Actually had a jr high softball game where there was a scheduling screw up, and the visitors never showed....and got the FULL game fee.
And if the contest starts late 30 minutes, we get a $25 late fee. I also work girls volleyball in the fall, and they started a policy to save travel expenses where the jr high teams play each other once, and then play a double match. We get a NICE $130 fee for that. So last fall, my partner banged in at the last moment one time, AND the visiting team showed up about 20 minutes late, so by the time they properly warmed up, it was late fee time!
(working alone is an additional 1/2 fee)
This is one of the advantages of having a semi-independent assignor, and having all of the fees and administration done by contractual rules. It takes a while longer to get paid - but we get PAID -everything that is due us.
And in ASA, no assigning gets done without money up front! This most likely costs us a league or two, but we never get screwed either!