They will eventually finish their shifts and alight at a platform; travelling as another passenger.
Average salary for a tube driver is £55k. Here's what TFL say;
“The average base pay of a Tube driver is £55,011. The overwhelming majority earned total remuneration – including base pay, overtime, employer pension contributions and certain allowances – of £70,000 [$80k] or considerably less.”
Always think that's interesting
That's a reasonable salary if you are expected to live (or commute daily) to London and provide something resembling a family home.
Everyone else in low and middle income bracket is just getting screwed.
As a software developer was getting paid less than a tube driver