> Just finding a GPS that understands vehicle heights and bridge underpass limits is still a significant challenge

Apparently for human drivers as well. Just this weekend, an overpass near my house had a rig stuck because the driver failed to realize his load was taller than the overpass.

Might be an incorrect sign. It does happen. A road gets paved and now is a couple inches higher and nobody bothers to change the sign. Any new bump, even one not directly under the bridge, can cause a collision. We cannot expect drivers to get out and measure every underpass ... thats what the signs are for!