Migrating toads

So I left work early to look at a project in a hospital, and then tried to leave Taunton. Rather than feed you AWAY from the road closure, they make you get stuck in the tail off traffic going into the only useful bit of the not closed road, wait endlessly at the traffic lights, then turn around and do it in reverse, just to get OUT of it.

It took me an HOUR just to get back to the road I wanted - is to get around the little bit of closed road. Which meant that my cunning plan to find nice things to photograph in the countryside were hampered by fading light.

There are any number of questions I have about this roadsign. I didn't see any toads bit this doesn't mean they don't migrate in that location. But my question is more about the fact that this is a WARNING sign.

Is the warning for the sake of the toads, or is it for the sake of the drivers? I can't imagine roads causing much damage to cars if you hit them, unless of course there were so MANY of them that the road surface became, well, squishy.