A typical London Bus does far more than 100 miles a day
Taking one route I drove, Uxbridge to Shepherds Bush, 15 miles, 1 hour, single journey
Apart from spreadover buses they were out there from about 06:00 to midnight, changing drivers
The scheduling dept had to be careful that the first buses out weren't the last ones in (05:00 to 01:00) as they may have run out of diesel
Taking off stand time that could be 250 to 270 miles a day