Slot machines pay out real money. It helps contributing to the illusion that you can recover from your losses by playing more. Football stickers, loot boxes, etc... make it clear that the money is spent.
I think this thread is missing the main reason why gambling dangerous: it can turn money into more money. The blinking lights and the Skinner box pyschology only play a supporting role to the main attraction: which is the belief that you can walk out richer than you walked in. This particularly plagues the poor, either because they are desperate or lack the financial accumen, and is the main reason why it is regulated. In the UK where sports gambling is legal, it is widely considered a blight on the lower class.
The fact the next roll could win back everything I've lost tonight AND make a profit on top, is far more dangerous than the next pull being merely able to finally get me that coveted Overwatch skin.
Hence why colloquially everyone calls loot boxes gambling, but no one has been able to make a strong legal case for why Overwatch loot boxes constitute gambling. If anything, Counterstrike is in the worse legal position and has had ACTUAL gambling scandals due to the high resale value of certain weapon skins.
And where would 2p machines [1] fit into this? It's acceptable to let your kids go on those and they have real money prizes.
That's not to say you're wrong though, because as I said I'm not really sure.
Those aren't going to break the bank though, or start a habit, so a harmless way to let the kids get rid of parent's pocket of excess coppers.