Don't confuse someone who is just trying to get away with someone who is violent or armed. If someone is fighting back, squared off with hands up, trying to use their skull to bash your face in as you hold them, or similar, the rules change quick. You aren't allowed to cause injury as part of detaining them. They can sue you over that and they will win.
You can see the loss prevention professionals detaining these people without causing injury. In both videos, they had them disabled and held. With that said, they weren't actually fighting back besides trying to walk away/get away. There was no directed attack in either video you linked to that I could see.
If you injure your wrists struggling against a tie wrap binding your hands, that is on you. If you fall and break your hands and fingers as a result of them handling you, that is on them. It becomes a gray area and legally sketchy very, very fast. If it isn't all on video, it can come down to reported injuries.
And again, just because someone is injured doesn't mean you are going to end up paying them shit, you may be found liable for their injury.
It depends. That is the biggest problem you've got. That gray area where a "no recovery no fee" personal injury lawyer will make your life hell. They aren't paid until you pay out on the injury so they have no incentive to go away until you pay something.
First, they have to sue you. Secondly, they have to win the suit.
It isn't hard to find a personal injury lawyer willing to roll the dice. "No recovery no fee" lawsuits are very common especially when the other party has very deep pockets. They have every incentive to be aggressive, creative, and a huge headache to get a settlement or win.
Someone suing for a sprained ankle
Fall down onto concrete and hit your head? Fall backwards after having your hands tied up with tie wraps breaking your hands/fingers? The list goes on for serious, life changing injuries that can happen in seconds. We're remarkably fragile and the actual damages could add up. Medical bills aren't emotional distress.
You can't think of a single retailer that has hands on LP? You must not know very many.
And finally, no, that isn't what the post above says. If you read, it says:
They will tackle you in the parking lot if they have to.
This would be exceedingly rare due to the level of potential injury.