There are ways to get residential proxies in a more ethical way these days. Some apps/extensions are now offering money for network access/network usage and they are open about what they are doing. They pay you with cash in exchange for your network, no covert VPN or sneaky SDK in unrelated apps.

I think even the more ethically dubious providers are shifting towards that model. Which makes sense since they have to pay anyways.

I'm skeptical even those services properly inform users about the risks and downsides. I also suspect those services turn a blind eye to resellers violating their consent policies

Alternatively, the users are well aware and embrace the plausible deniability it lends their own traffic.

I think the experiences of people operating open relays suggest that would be a foolish assumption.

If you tell a police search team you have plausible deniability they will seize all your tech and investigate you. If you're actually guilty there's a decent chance there will be other incriminating evidence. If you're innocent this will be unpleasant, expensive, and they might end up finding what they think is evidence against you anyway

see: https://earnapp.com/