A mix is what’s needed. Trains between major metropols, busses for smaller places. Less frequent busses for yet smaller places and no busses for the most remote locations.

I have used public transit to several remote locations in Scandinavia, it’s surprisingly doable, but it takes planning and often waiting because there’s only one bus a day, the school bus (but anyone with a ticket can get a ride).

Still, having the option to travel with public transport and have the opportunity to read my book, doze off or just relax is amazing.