It's called personal responsibility. Those fish are actually good snail eaters, so if i had a six foot tank and a snail problem, that's really not a bad price for a couple of those 'packs'. People have a responsibility to find out the appropriate care needs for whatever creature they buy, and everyone has access to this information online - there is no excuse. It's a shame for the fish who are bought by people who don't take a few minutes to check, of course, I don't dispute that - I got pretty irate listening to a woman go wanted two small orandas for her 17 litre tank the other day, but there wasnt a lot I could do about it so I just moved away.
It doesn't say on that site 'these grow huge, you need a tank X size', but nor does it say 'you can keep these in a little hex on the kitchen side' either. It's the buyer's responsibility to find out.
Even a certain chain that everyone slams on here has a sign above the clown loach tank listing the size they can reach. Same with the plecs, the sharks, even the goldfish. It's there, in black and white, next to the price. Personal responsibility of the buyer to read the information given to them. They don't even have to go away and research.
Business is tough these days, the morals and ethics of keeping clown loaches don't pay the bills.
/www.aquaticstoyourdoor.co.uk/Snail-Eating-Cleaner-Pack.html
Might get some ! 
