Can debt collectors legitimately chase up indebtedness like this that was incurred/created when a person was 17, or do they simply wait until after that person is 18+?
All depends what the debt is for.
I'll try to keep this as short and sweet, but you've opened a can of worms here slightly.
First and foremost, debt collectors have no legal authority and have no more legal entitlement to chase any civil debt that myself or you do. Civilian debts can only be validated in the court and only after that can they be legally enforceable, though it won't stop debt collectors sending letters before that which make them look like bailiffs in order to frighten people into paying.
As for the age thing. Under 18s can only enter into a contract if it's a contract of necessity (children and families act/Family reform act) Contracts of necessity only cover things like the purchase of food and clothing etc (sale of goods act) or for employment and accommodation, so if a minor was sued for anything that wasn't a contract of necessity, then the judge would deem the original contract invalid and through the claimants case out. Private parking invoices aren't a contract of necessity so aren't enforceable against a minor in court so that's an example.
You cited about waiting until they turn 18. Again in the scenarios I outlined, it's irrelevant because the contract would have been entered into when they were a minor so the contract is invalid regardless however old the defendant may now be, just like in a criminal court if somebody who's say is 25 is charged with a criminal offence that was committed when they were say 15, then they not only have to be tried as a minor but also sentanced as a minor and under sentance guidelines at the time of the offence.
Back to the original debt collector topic and the thread in general, I have no idea if the original purchase of rail tickets is seen as a contract of necessity or not, hence my can of worms pun.
