It's not that mobile is fast, it's that home internet is slow. It's the same reason home internet in places like Africa, South Korea and Eastern Europe is faster than in the USA and Western Europe: home internet was built out on old technology (cable/DSL) and never upgraded because (cynically) incumbent monopolies won't allow it or (less cynically) governments don't want to pay to rip up all the roads again.
Several Western European countries have deployed XGS-PON at scale, offering up to 10 Gbps, peaking at ~8 Gbps in practice. Hell I even have access to 25 Gbps P2P fiber here in Switzerland.
Also you can deliver well over 1 Gbps over coax or DSL with modern DOCSIS and G.fast respectively. But most countries have started dismantling copper wirelines.
Very few people have home equipment that can do anything close to 10Gbps, of course; this is all largely future proofing.
Years back, when FTTH started rolling out in Ireland, some of the CPE for the earliest rollouts only had 100Mbit/sec ethernet (on a 1Gbit/sec service)...
