No they aren't. You have to pay your workers and you have to pay them enough so that they don't tell you to go pound sand and work for someone else.
No worker HAS to work for you, will they, nil they. That IS slavery. If they can leave, it's not. I think you need to go look up the definition of 'slavery.'
So, if I own a store and want to hire someone to sell yarn, I'd better offer enough to make someone want to work for me. If I don't, nobody will. If I don't offer enough, s/he will leave and work for someone else. If I'm the only employer in the area, I'd better take good care to offer good wages, because union strikes are not good things.
........I don't see 'slavery' anywhere in there. It's a bit odd that you do.