Twist the question the other way. What would happen if there were no ROSCOs? There'd still be accountants assessing the book value of rolling stock and allocating it to areas who paid the most for it, there'd still have to be someone in charge of these scarce resources - it wouldn't just be a Sir Topham Hat arbitrarily dishing out trains on a whim - we'd still have the same arguments (in the way that some people are slowly realising that our GBR future isn't going to solve all of the things that they moaned about during the privatisation era... some people are realising this anyhow!)
Also, if the ROSCOs charge so much then how come the financially astute people like Brian Souter never called their bluff by ordering some Turbostars directly from the manufacturer? Given that, if the ROSCOs are supposedly bleeding the industry dry, you'd expect to be able to make your money back on a direct purchase after a few years - there'd be a resale value - especially if you stuck to just ordering a fairly "go anywhere" train... (instead, despite Stagecoach running hundreds of buses around Great Britain, they choose to lease a lot of them, because they find it better to do that, even if they expect to be the only operator of that vehicle during it's fifteen/twenty year life)
Should the Government borrow the money to buy the trains, in which case you need to take into account the interest payable, perhaps long after the trains have been scrapped? Or should it raise taxes or cut expenditure on, say, the NHS, education, welfare or public transport?
This is the problem
Whilst some people want to go down the path of "Government debt is so cheap that it's virtually free to buy new trains, compared to the entire annual UK Government expenditure", they do cost a lot of money - millions of pounds per unit - and any Transport department has to fight for that money against other departments - it's always going to be tough to prioritise a hundred million pounds on your pet transport project when that would pay for however many Nurses/ Teachers etc - I'm not saying I agree with this but it's the political reality and we have to accept that
Not to mention the fact that the traditional ROSCOs have a much better idea of how to negotiate with builders, hence why 802s are less of a problem for GWR than the DfT specified 800s.
That's a good point
A lot of the worst public sector spending is when people buy things that they aren't used to purchasing - e.g. a smaller council area undertake a "once in a generation" project where nobody has the experience of last time they procured that thing
ROSCOs know how to negotiate with train manufacturers, ROSCOs have a vested interest in ensuring some commonality with existing trains where possible (rather than seeing every order for trains designed as some "bespoke" delivery) - there are some upsides to having such middle men
Introducing leasing companies into the rail industry is one of the biggest scandals of rail privatisation, in my view.
They purely exist because of political ideology
Didn't BR lease some locomotives though?