However, the more common scenario when consulting -- and I'm sure many are nervous about this type of play-out -- is the client drags the deal on and on and on...and argues about the price...and pays late...and has endless change requests...and is surpirse that ECRs cost money...and needs just one more meeting about $THING..and...and...and.
I've always assumed that's why we've been rejected...how can someone tell we're NOT LIKE 90% of the consulting buyers and mostly know what we're doing and have a straight-forward deal?
Were they administratively prepared to accept payments? For instance, did they have business bank accounts, invoicing, tax numbers, record keeping - if not, then it would be a hassle to do all that in order to receive a once-off payment for a days work, even if the rate is generous. Indeed, they'd need to "go commercial" to make the hassle worthwhile. So it may not be as cut-and-dry as you thought.
Basically unless you're already making a living by the accumulation of a lot of that kind of $800 transaction, the hassle involved in accepting just one of them as a one-off makes it not worthwhile (tax questions, potential conflict of interest with existing employer, dealing with people as paying clients rather than as people one can simply say 'no' to, etc...) And there's a massive chasm between "maybe once in six months somebody offers you $800" and "enough money coming in to quit the day job".