How big is the swamp?
Consider it’s almost the size of a state.

Okay, granted: I picked the smallest state. But still.
Rhode Island is 1,214 square miles compared to the 1,139 square miles of Big Cypress Nat’l Preserve alone. If we add in Fakahatchee and the rest of cypress tree country, the swamp definitely wins.
As for the levees, the L28 South (plus tieback) is 19 miles long. The L28 Interceptor is 18 miles long. The West Feeder another 5. That add up to 42 miles of levee, and about the same length of I-95 in Rhode Island.
The key difference is the traffic congestion and speed.
I-95 is a major high-speed thoroughfare …
While interstate-sized levees are barely traveled at all.