Of course many people have jobs that canâ(TM)t be done from home, so to them people complaining about 3 days a week at work donâ(TM)t get a lot of sympathy.
Different jobs have different conditions, things you should have considered when choosing a career path.
Also for those who do still have to travel, removing millions of unnecessary commuters makes the journey a lot better - its the difference between an hour in traffic or a 30 mins easy drive, or having a seat on the train instead of having to stand for an hour. Long term it also serves to rebalance property prices so that you don't have to pay exorbitant prices to live close to your workplace.
Three days vs 0 days is a big step down because:
1) you still need to maintain a vehicle if you drive to work, vs possibly doing away with the vehicle entirely (many households have multiple cars for commuting but could do with just 1 or even 0 otherwise)
2) you still have to live within commuting distance of the office, so your still stuck with higher property prices
3) if you travel by train or bus buying 3 daily tickets is often only slightly cheaper than a weekly or monthly ticket
4) the company still has the full expense of maintaining the office, even if it now sits empty for 4 days per week
The best thing for the company, the employees and the environment is to have people work remote if the job allows for it.