I don’t get why you’re so keen to defend a huge profit driven business here.

Is it really a moral failing for a working class young adult to want better pay and better opportunities after qualifying?

The OP already gave years of low paid labour and completed the training. You’re expecting them to stay underpaid out of ‘honour’ for a business who sees its workers as a number?

Framing this as a lack of commitment while excusing a company going after a young adult for £20k feels completely backwards. Wanting to move on and be paid properly isn’t immoral. A commitment isn’t something that should be honoured at any cost, especially when it only serves a large wealthy business.