Because they wait for corporate server half the world away logging every click through crappy 2g connection before they can advance to next screen. How I know? I made some telemetric devices working on 2g connections, trying to optimise the hell out of it (other hardware vendors look at you funny when you tell them that your devices use only 2MB/month). Minimum response time was about 1.5s, 20s was still pretty normal.

I’ve found using my knuckle helps immensely.

Still slow, but touches register more consistently.