> The difference is that those extra lanes take up physical space, which goes unused outside of rush hour, while increasing frequency of eg trains or trams does not.

To increase the capacity of trains and busses, you need more trains/busses, larger trains/busses, more train/bus operators, more electricity/gas usage, more storage, more maintenance, and so on. And those same huge trains and busses also become near-empty late at night.

Yes, the baseline efficiency of a train or bus is potentially better, making all the standard tradeoffs. But everyone commuting at the same time causes similar problems with both. I'm not arguing against public transit, here, I'm arguing against the claim upthread that "This is a problem of a car centric society", which is orthogonal to a staggered commute.