Here's a counterpoint:

https://www.curbed.com/2021/01/elon-musk-miami-tunnel-boring...

The counterpoint is valid (rising seas don't help), but then we have Saint Petersburg ([1]) that's literally build on top of swamps and occupies multiple islands. It has a first class subway ([2]). It's a little deeper than regular subways, but it exists and works really well.

1. https://en.wikipedia.org/wiki/Saint_Petersburg

2. https://en.wikipedia.org/wiki/Saint_Petersburg_Metro

Forget the tunnels, sealing those is commonplace, what really matters is the station entrances. St. Petersburg station entrances were built well above sea level, and by "sea level" I mean the level the builders expected for the foreseeable future.

I think the problem with Miami is the limestone not just the swamp fact.

Just Elon, 5-hour Energy & a shovel