That's a bit naive view - people sitting at home in misery didn't do a squat re car/travel pollution. Massive container ships output much more, and what did everybody? Switch even more to internet deliveries, be it food or everything else. Unless its produced locally it comes from far.

Bigger effect would be shutting of factories, but then again we're talking about millions of blue collar workers getting potentially into serious financial problems with little help - hardly something to cheer up for.

To have any visible effect from transport on environment we would have to be stuck at home for maybe 20 years.