I would actually write and complain to the branch manager. Accuse the member of staff of pushing credit onto people that can't afford it and misleading customers with the implication that this 'entitled to' loan has been pre-approved. Banks are scared shitless of another misselling scandal. The cashier will be on a commission for every loan they sell and needs reminding of the rules.
Whether she would get it after the form-filling is hardly the point, is it? The point is that it's a hard sell, it puts the idea of loans in people's heads, when they wouldn't otherwise contemplate getting one. Then, if they are turned down, they feel dissapointed, almost like a failure.. All psychological
The credit rating bit doesn't necessarily apply. My bank were able to offer me a loan based solely on my banking history with them. It was pre-approved, they didn't do a credit search, I filled in a rough outline of my income and outgoings, but with a lot of room for 'data manipulation', shall we say (no evidence was required of anything - it was based on my own disclosure).
I think they're trying to take it back to the old days when the nice friendly bank manager would base a loan approval on having known you and your mum for decades, and lend you the money because you had a trustworthy face!
In my circumstances it's a welcome change - they can see from my 8 year history with them that my earning potential has increased, as has my ability to manage my finances responsibly. However, in the OP's case, it reminds me more of my old bank who, the day after my eighteenth birthday (while I was still in full time education) sent me an application for a credit card. They then approved this application, and gave me £2000 of credit. Let me repeat...I was in full time education! The consequences left me in debt for years. Yes, I take responsibility, it was my very poor attitude to spending, but they should never have made that possible for an 18 year old.
Cashiers aren't on commission (at the bank I work for the sales people aren't either but that's beside the point). They are targetted on referring a certain number of customers to a sales person, but this is part of their job, not something they get paid extra for! Having said that, I would ask to have a word with the manager as this to me would not be acceptable from a staff or customer perspective and I know of cashiers who have had a slap on the wrist for this. All the cashier will have based this assumption on is an overview of how u manage your accounts there, and will not have looked at income/ outgoings and CANNOT credit score you. I think it's a bit of a stretch to try and say this is why the banks are in trouble, because 1 member of staff worded something incorrectly!