[Someone]

It has but not for mountain lions. The likes of toads and hedgehogs only need a small below-ground tube (https://en.wikipedia.org/wiki/Davis,_California#Toad_Tunnel), squirrels and marters can be helped with an above-ground rope (https://en.wikipedia.org/wiki/Squirrel_bridge)

One issue with narrow passages is that predators may learn to take advantage of them, eventually driving other wildlife away.