I know it sounds dumb for them to throw them away. A better recommendation would be for them to just take them to the local Salvation Army or homeless shelter.
Either way, people shouldn't be leaving their laundry unattended... and if they have to leave it unattended, then don't leave it unattended too long.
When I do my laundry, I stay with it the first few times I do it so I know how long it takes for the washer and dryer to run. From there, I'll know when to return when I do my laundry unattended.
From my experience, the dryer usually takes 45 to 50 minutes and the washer takes 15 to 20 minutes. Don't those public dryers have timers on them? If so, then you should be able to tell when to return (and return within a few minutes before the time is up so that you can move your laundry in a timely manner.