It makes sense if you understand how banks work. They are there to increase the amount of money in the system, hence they will lend out anything up to ten times the amount of capital they have as assets.
That means that a bank with £1000000 worth of assets can lend out £10m, though always spreading the risk by lending lots of smaller amounts.
If you do your sums its obvious that the bank only has to reclaim 10% plus administration fees to break even on each debt. So if you owe £40000 I assume you must have paid back well over £4000 to have ramped up to that much debt in the first place.
A combination of very low interest rates and massive competition in the market place (everyone is getting in on the act, supermarkets, storecards etc) has led to the scramble from credit companies to offer credit as widely as possible. However with the new bankruptcy laws it does make the credit companies rather vulnerable to the (somewhat) unscrupulous. Its not as though the poor babs make any profits....
It's worth noting that student loans from after (worth checking) 1998? are not exempt from bankruptcy due to an oversight in the bill. This means that many students can leave university, declare themselves bankrupt, and rid themselves of anything up to £20k worth of debt. They will also be more attractive to future lenders due to a clean slate than those who choose to remain encumbered.
With the rediculous tuition fees and massive overdrafts this would appear to be a very sensible option given that most degrees are now barely worth the paper they are printed on. Indeed an MSc nowadays is probably worth a degree of old. If a student thinks that paying off £20k over three years is likely given their realm of employment then fair enough, though surely a further £10k (depending on the course, many MBAs require £15k+ tuition fees rather than the standard £3k for an MSc, though often along with plenty of time in industry) spent on a deferred post graduate loan to cover tuition costs and living expenses for a year long MSc would be a more viable option.
This would increase potential earnings with the catchall option of bankruptcy should the poor dear be unable to keep up with repayments. With a 50% target for school leavers entering University I would think this to be one of the few ways to stand out from the crowd.
After a single year in gainful employment said student could then be in a high earning job with plenty of spare cash to spend on flying.
Just another option.