I'd agree with other commenters here that it seems pretty expensive for what you're getting, or at least the value proposition is poorly presented. For example, I don't see any reason why I'd want to pay for this at a US airport (at least from the perspective of a US citizen). On the other hand if you told me the immigration line at XYZ airport was typically 45-60 minutes long and you could guarantee me priority access, there is a value there that I might pay for.

The pricing also seem really opaque - the prices even within a single country vary (from $250 at JFK in the US to $375 at SFO, why?). Certainly the going rate for a fixer at the location must play into this, but from a customer perspective I'd expect the fee to mostly depend on the value to me - I'll pay more if the expected level of delay or hassle is high. That might actually be inverse of the rate you pay the fixer - there's less value in US/Europe for me than if I'm traveling in e.g., Southeast Asia.

Overall though I think this is an interesting idea and I'd be a customer at the right price point, at least for certain destinations. Good luck!