[tialaramex]

The nominal dealing on a future's market will be on some paper that entitles the holder to the commodity delivery at a future date. When you buy oil futures, you are NOT buying oil since the oil doesn't exist (well I guess it exists underground somewhere, maybe), you are buying a contract to deliver crude oil and that needs to really exist. If the contracts don't exist that's a Bucket Shop.

It matters when things go badly wrong, because with a Bucket Shop you're left penniless, it was all imaginary anyway. Whereas with a futures market even if the exchange blows up those are real contracts you can sell to somebody who wants the commodity you were trading in, at worst a mild inconvenience and a small haircut to your final profit.

[amluto]

You may be confusing the exchange with a broker. With a serious commodities broker, you’re using the services of the broker to trade on an exchange, e.g. the CME. The broker does not particularly care whether you make or lose money, so long as you don’t actually go negative.

In the US, securities brokers are very heavily regulated — see “regulation NMS”.

[tialaramex]

I don't think so (I am not an expert though so it's possible), my point was that even if the exchange, not just your broker, blows up, the thing you were buying and selling is a real thing anyway, unlike in a Bucket Shop.