Maybe in fancy "I make this shit up" land, but in real life that's not how businesses work. Most medium to large businesses operate on net 30, if you think they will operate on NEGATIVE net 30, you're a fucking moron.
Make people sign a contract, even if that shit won't hold up in court most people will not fuck you over $200 if there is a chance for getting sued. Some guys are douchebags and will try to fuck you and that's when you take them to small claims - in most cases it'll be open and shut.
Bollocks.
Just because their account depts work on NET 30, doesn't mean they won't pay up front if their CEO / COO / CFO tells them to.
If this is from your experience, you need to stop buying into their bullshit and tell them straight what your terms are. I've been money up front only (100% for consulting, 50% for projects) for 5 years now, and haven't lost a single sale because of it. For 12 years' previous to that, I gave credit as a rule, and lost over $60k in bad debts, mainly to companies that went insolvent (so no small claims). Screw that. I'm not a fucking bank.
Not interested in court, because even if it's open and shut, you gotta wait 3 months for a court date, and then you've gotta collect on your judgement (people always seem to forget about that bit). If they don't have any realisable assets, it's Good Luck Bros. Same if they do a phoenix (wind up the company and start another).
Personally, I'd rather not work at all for someone than work not knowing if I'm going to get paid.
The only possible exception to this is if you're selling something that's part of a supply chain (like selling camshafts to an car manufacturer), or selling goods for resale. That's what "trade credit" is intended for, not allowing someone to take 3 months to pay you for consulting work.