I’m thinking of security-oriented code-reviews of various enterprise software. One of my old clients commissioned some last year over a piece of work I made, and apparently they had to go “to hell and back” to source a reputable (and very expensive) reviewer somewhere in California, while I’m sure there must be plenty of UK talent available. They then had someone else pentest it as a blackbox, which is definitely easier to source locally, although the quality can be very variable. I understand it is a very sensitive area, maybe it needs some sort of professional body to provide accreditation and self-regulate and promote reputable members, I don’t know.
I think bounties are an unbalanced system; as you say, pentesters don’t get paid for their time and often don’t get paid at all, like in this case. There must be a better way, where an independent third-party can judge actual severity of the hole and sanction payments.