I don't follow why an mcp server buying a 50 dollar flight would make costs to up? Surely an mcp server booking flights doesn't mean there is more demand for flights overall? I'm not about to take a trip somewhere just because I have an mcp server to book it.
Because like with everything else people have been applying AI to, it's not going to stop at "I used it to book my flights" and it's going to turn into "we used it to book every flight and now we are reselling them at a massive markup so we can then use it as an excuse to spam you because you signed up for our 'service' and that counts as 'consent'."
If you were going to take a flight anyway and it finds you a 50 dollar option instead of a 200 dollar option, that's very expensive for United.
if you're paying for flights you don't want to take, then I'm sure they're happy for the extra spending money of course. Why would you want to do that?