Does 'small business' mean 'bank' to big business?

I've seen a number of comments lately in different forums regarding the growing tendency for corporate enterprises to impose longer and longer payment terms on their suppliers, and then to make late payment, even when their lengthy payment terms are reluctantly accepted.

Mine is a small business. My success relies in no small part on my ability to maintain cash flow. So whilst there might be a far-flung universe that I've yet to encounter in which I might gleefully agree to 90 or 120-day payment terms, the bank that holds my mortgage will never accept the same.

Regular cash flow allows me to provide services to diverse organisations, most of which have a far, far bigger turnover than I dare aspire to. So why am I expected to pay for the privilege of delivering value-added services to multi-million pound organisations that would, after all, have to pay me monthly if I were an employee?

Perhaps there should be a little more realism in the expectations corporates place on the small business experts they rely on.