"Nonsense" would only apply if practice were as good as theory; a very very brief Google search will net plenty of results for freeway overpasses and pedestrian bridges being hit. One example:
This isn't really a criticism of the core idea to just say "what if somebody built it stupidly low", traffic lights have been fine my entire life and maybe some highways will have to be skipped or doubled for NASA/ military purposes.
https://www.cbs58.com/news/truck-wedged-under-bridge-shuts-d...