Advantage to the debtors.

[Oh_hunnihunni]

what they really need is cash sale accounts for these folks that gives the good discount but requires payment at the time
(Not just a stupid loyalty card that might get you a free coffee once a week or a pittance off ).  Would seem to be a win win for everyone...  Do they exist?

Quite.

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That could be useful as a larger version of "loyalty" cards to prove that you are a regular customer, but doesn't really help to secure credit, other than giving someone a chance to build a relationship with a business. To change from cash to credit would still be a risk that requires some kind of credit history. When I was hit with this in 1980 I was told to go and get a credit card, which I did and therefore didn't need the hp I was asking for.

For OP's example no amount of loyalty cards will help to identify the person as a legitimate trade customer. That part is not about cash versus credit, but about whether you are bona fide when you don't have references from others in the trade.

I was not wanting credit.... they were happy to give me a discount so long as I had an account.,.. and fyi last time I dealt with a branch of that firm.. some years ago now in  one of many loads of timber I had 17 Tonne of palings delivered to me...

That is one Very Long Picket Fence. Kudos...