Because they are employed by that company and have to abide by their rules. If they say they need to show up for work in the office, then that’s what they have to do.
There is a LOT of exploitation among teleworkers - all summer they’ve been at the pool, hogging the chairs in the shade! - and a company might decide it’s more efficient to just have everyone come back to work.
I already said it's up to the boss. Who are you arguing with?