Bridges can be really hard to take out, depending on the kind of bridge and how it was hit. If the bombs just punched a hole in the deck, that’s a pretty easy repair. The Kerch Strait bridge has been hit by Ukraine many times and is still standing and has been fixed (arguable though that Ukraine hasn’t yet intended to bring it down). The Francis Scott Key Bridge was just demolished. When it collapsed, there wasn’t really anything worth repairing left. Which means it isn’t a quick repair job, it’s a whole new build. And some kinds of bridges are way easier to build than others. A big suspension/cable stayed span/etc bridge is a major undertaking. A simple causeway type bridge, not so much. Also much harder to completely destroy - you can damage sections, to be sure, but most of the rest of the sections will be relatively undamaged unless you specifically hit them too.