Why not using a web site built on postgres or mysql database to track balances then, instead of using blockchain and call the thing "cryptocurrency"?
You can think of this as a "coin" that's pegged against prevailing currency (in my case, the yen). It's not a "cryptocoin" since there is no "crypto" involved, but as there is barely any "crypto" involved in cryptocoins anyway, I think that's a bit of a moot point.
There are problems with this model. First you have to trust the central authority with your money. They could do a runner and there would be nothing you could do about it. In fact, when I lived in the UK, I discovered that London Transport often mischarges - it forgets where you "tapped in" or "tapped out" and charges you the maximum possible charge for your journey. In order to get your money back, you have to register your card and apply within a specific time period to get refunded. If you don't know the procedure, don't want to give out your person information, don't realise you were mischarged or wait too long -- sorry, your money is gone (Really big piece of advice for anyone using an Oyster card: Register it and check the charges every day. Unless things have gotten better in the last few years, I'm sure you will be extremely surprised at the charges).
The problem here is that the payment processor has all the power in the transaction. They can just take your money if they feel like it. Also, they can refuse to pay for things if they feel like it. Finally, they are a single point of failure. If they have technical (or financial!) problems, then you may not be able to spend your money.
Whether or not you assume initiatives like Bitcoin were started as a scam, the implementation potentially solves a lot of the problems of these payment processors. Importantly, if you put your coins in a central exchange you are right back to square one! No amount of crypto goodness will save you from the exchange shenanigans because they control your wallet.
This is why things like the Lightning Network are interesting. It allows for centralised payment processors, but with distributed guarantees about who owns the coins and where and when they can spend them.
I find it incredibly unfortunate that "cryptocoins" endure such incredible hype and involve so much real (and imagined) money. So many power plays, so many scams, so much FUD. But at the centre of it, these are interesting real problems. Once the dust settles it will be quite nice to see what useful results actually emerge.
The blockchain is an interesting Computer Science toy. But in the 10+ years since it was invented, the only real application that anyone has found for it is Massively Distributed Ponzi Schemes.
The problems that you point out with London Transport aren't solvable by a distributed blockchain, because London Transport is a single central authority. It's completely pointless creating a distributed ticketing mechanism for them where they don't have all the power, because the ticketing mechanism is for the trains that London Transport run and control completely. There's no point having a ticket that London Transport don't recognise as valid. They're always going to be a single point of failure because they run the whole system. Sorry to be so blunt about it.
The solution to this problem is not to add in MORE complexity, networking and distribution. It'll be in removing complexity and improving connectivity.
But, of course, your stock price doesn't increase by removing complexity. You need the blockchains to impress the idiots who buy shares.
It's interesting that you say that creating a payment processor for transportation fares that is not controlled by a monopoly is pointless. I currently live in a country that has at least 5 payment processors for train fares and it's taken them decades to figure out how to interoperate Even now I still can't use my rail card in Tokyo.
These are real problems. "Computer Science toys" seems like another word for "research" to me. That the research was done by some random guy on the internet with unknown motivations is completely beside the point. Yes, like most people, I could definitely do without the scams. I could definitely do without the "OMG! Blockchain" knee jerk reaction. But would it be too impolite to also complain about the "Blockchain? Pfft!" knee jerk reaction? Lightning is a great example of a useful protocol -- full stop. I don't care if it's implemented on top of Bitcoin or on top of some byzantine 18th century payment exchange based on carrier pigeons. We need more of this stuff, not less.
I totally agree about pure research giving us CS "toys" that eventually turn out to be useful. But we've had ten years to find some use for blockchain that isn't cryptocurrency, and as far as I'm aware, no-one's found one. My suspicion is that this is because the problems that the blockchain solve only rarely need solving. It's unlucky that one of those rare occurrences is currency, hence all the bullshit.
Can't this be done with something like git?
Dollar signs a person doesn't understand but sees as easy cash is the equivalent to a lightbulb being turned on amidst a swarm of insects.
(I think there are better ways to do this than a blockchain)