The obvious solution is the status quo contactless payment system that can collect £4.90 from your wallet faster than the ticket holders can find the slot.
Even if London Underground decided to upset millions of commuters by raising the price to a round £5 in the most expensive attempt to rescue an incorrect HN claim yet, the contactless system would still be quicker than the machine that scans a fiver. Trust us, we've actually used both...
Your claim was that it isn't possible, but it is possible as evidenced by the fact that it has actually been done in the past.
> Even if London Underground decided to upset millions of commuters by raising the price to a round £5
If people would really be so upset with a 2% fare increase then imagine how happy they would be to round it down rather than up. It's even good policy -- encourage mass transit over driving.
For that matter you could issue single ride transit tokens for whatever exact price you like. The point of cash isn't to use a specific currency, it's to allow people to travel and make small purchases anonymously.
Even what NYC does now is better than using contactless payments, because you can buy a Metro Card for cash without providing a name. It's not quite as good because they still track the cards, but it's still better than having all of everyone's movements perfectly tracked by an Orwellian state computer.
> the contactless system would still be quicker than the machine that scans a fiver. Trust us, we've actually used both...
Comparing the fastest available electronic system to some kind of anachronism with paper tickets and slow readers is obviously going to favor the newer system -- although even then it's still a matter of seconds. But how is that the fair comparison? The comparison has to be between the best available electronic system and the best available cash-equivalent system that preserves privacy.
And dropping a dollar coin or a transit token into a slot in a turnstile is as close to instantaneous as makes no difference. Certainly not enough to justify tracking everyone's movements.
Even if London Underground decided to upset millions of commuters by raising the price to a round £5 in the most expensive attempt to rescue an incorrect HN claim yet, the contactless system would still be quicker than the machine that scans a fiver. Trust us, we've actually used both...