Hi,
The trouble is there are many different types of fords aren't there.
Some are simply roads that flood.
Some are proper moorland fords across streams with rock beds.
So you just make a decision as you find them, well freewheeling would be okay if you've got enough speed and are short enough, if you can see the bottom then cycling through slowly even if your pedals go underwater you can shuffle the pedals to get through without getting your feet wet.
The footbridge can be useful but they're not always wide enough are they, as said, And originally they would've been made for pedestrians.
Likewise with moorland fords The stones can be rocks and they're not always flat.
Stand on the stones and push the bike through the water, I did that once in 3 foot of water on a Moorland Ford, The contents of the panniers were wrapped in thick plastic so bike just floated at the back
in the case of cars it's obvious that some people haven't got a clue what speed to go through flooded water, they think they will get stuck so they accelerate.
If I was presented with a problem with four wheels I would wade through To test the deepness of the water first, then if you've got half a brain you can decide whether it's too deep or not, that is whether it will flood the engine.