In many (most?) countries mobile data is cheaper than wired connections, but obviously with worse latency.

Slower too maybe, but we're long past the point it really matters, except for latency sensitive applications. 50+ Mbps is just plenty for most applications.

Only real need of wifi to save some battery power and maybe to get better latency and jitter for VoIP and interactive applications.

AFAIK, US and UK are still pretty bad. I guess they have to limit bandwidth and data volume to be able to, ahem, listen to their customer.