AC and "recharging" - scam ?

You hear all the time about people saying that the AC in their car "just needs to be recharged", however, I read somewhere that it isn't true as the AC system is a sealed/closed system and doesn't "run low" on refrigerant and the whole recharging thing is just a scam. Or if someone is trying to sell you a car and says that it just needs to be recharged, that there is a bigger, more costly problem to be dealt with..

What's your thoughts?

The refrigerant is usually low when there is a leak. In that case, recharging is only a temporary fix which keeps the actual problem unattended.

Ah ok, that makes sense then, thanks!

You hear all the time about people saying that the AC in their car "just needs to be recharged", however, I read somewhere that it isn't true as the AC system is a sealed/closed system and doesn't "run low" on refrigerant and the whole recharging thing is just a scam. Or if someone is trying to sell you a car and says that it just needs to be recharged, that there is a bigger, more costly problem to be dealt with..

What's your thoughts?

If it is low on gas there will be a leak someplace.
Very few just need a recharge without finding the leak and fixing the problem.
And sometime the problem can run up into the K figures.
Some older R-12 systems would have cold weather seap/leaksand would be good for 1-3-5 years with a recharge.
But not many of them left.