That’s called “literally doing nothing”. If all he’s doing is running away all the time, it’s pretty easy to out pressure him in lane or a teamfight. You don’t have to kill him to make progress on the map. He’s very hard to kill by design, but he also isn’t doing much if that’s all he’s doing.
This is also true for Sylvanas, Maiev, and Tyrael, don’t chase where they’re going, chase where they’re going to go. If they can use a highly-telegraphed mobility spell, you need to keep a mobility spell of your own handy to chase when they swap.
Don’t have a mobility spell? Tough, your hero can’t chase Samuro. So bring a friend to gank him instead, or just don’t waste time bothering.
Considering he has to use Mirror Image, Image Transmission, AND Wind Walk to get away when most assassins just need one ability, that’s the trade-off.