On self spray car washes, it always says, " no buckets".

But I see people with buckets all the time, soaping up their cars and trucks...

But all the self-sprays around here you can't stop the machine from running/time ticking down once you enter your $2.xx ....

So how the hell do people do it? Or do they just waste $2.xx on filling up their bucket and doing a pre-wash?