I think that if you are at the start of your career you are more likely to be concerned about meeting people and learning from colleagues. You probably won’t want to live with your parents or commute from the Midlands. But that’s for another discussionThe thing is, though, if you're at the start of your career you no longer have to live in a "crappy flat" and work "on an ironing board", because you no longer need to live in London (which is where this mostly goes on due to the outrageous property prices). You can get the gains mentioned by going in 2 days a week, and that can allow for a longer commute, e.g. from the Midlands where housing is cheaper. Or perhaps it'd be viable to stay with your parents for a few years and save for a deposit on your own place. Benefits all round there.
But either way, where people work is not a matter for the Government, and their nose needs to be kept firmly out of it. It is a matter between employer, employee and (where applicable) Union. There is the H&S aspect, but (pre COVID) just making a declaration has handled that in a way people are generally happy with; perhaps a right to employer funded "proper" desk/chair might be worth considering, that said. The Government has no business encouraging travel, when travel is to be discouraged because of environmental issues. If that causes Pret issues, they might want to consider setting up cafes in residential areas instead for homeworkers to pop out for lunch (I often did this pre-COVID). If it causes the railway issues, that needs to restructure around the actual travel demands that are presented to it, not set about creating them.
I could not be more opposed to the idea of a policy of legally-enforced Luddism.