You might be detected but if, for example, you were smart enough not to MITM the same client twice after an error, I suspect a ton of people would ignore it and just assume the airport/coffee shop WiFi was flaky.

I’d also bet more things use libcurl behind the scenes than we appreciate, and that at least a few of them have things like silent updates which retry after a failure without notifying a user. I’ve seen a lot of agents which just try to periodically check in because they’re designed not to be noisy on lousy networks.