I mean... Casinos are all a big scam to begin with lol

The reason they're profitable is because all games have a negative average EV (expected value) for the player. Card counting allows you to play in a manner that is +EV, so it has to be banned.

Yes. And yes.

They mostly don't care unless you're at the high roller table. And even then, unless you're using a device to cheat, the most they can do is pay out your chips and escort you outside. It's not a crime to count cards, but it's still their table.

I saw a video on this recently. I think it was Wendover.

Though card counting is still possible many casinos have made it very difficult. Most methods require the counter knowing what is left in the deck.

Two methods are just using 3-5 decks and reshuffling the deck after eatch hand. This apprently stops all but the most insanely talented card counters. Some go further using a machine to shuffle the deck in a way players can't see.

Though it also mentions some players think this cheating for the house so it might not be done at every casino

Its not meant to be a skill game. You can make it one, but it's intended to be a game with fixed odds that favor the house.

With that being said, in places where they're legal casinos tend to have really broad leeway over who they're allowed to kick out and why.

These days, casinos are trying to eliminate "skill" from blackjack entirely. You'll have six decks, and as soon as a hand is done, everything gets shuffled back together. That makes counting cards practically impossible, even with perfect playing. Counting cards mostly works when you're playing with a single deck, and it doesn't get shuffled immediately after each hand.