Here's another idea which I tried to launch, back when I worked for a phone company. Disposable phone numbers.
The pitch was simple. "As a woman on a dating site, I don't want to give my phone number out to strange blokes in case they don't like it when I eventually reject them."
The idea was that we'd partner with a dating service and, for the low price of £X per month, give users a temporary phone number. Calls and texts to that number would be routed to the user's regular phone number. At any time, the user could hit a button and the temp number would be deleted. Bang! And the harasser has gone!
The model also extended to pizza delivery companies, couriers, taxi firms, plumbers etc. There's a whole raft of people you might not feel comfortable knowing your real number - so buy a disposable one from us and discard it if anyone starts being weird with you.
This has now become mainstream in the tech world with Apple's Hide My Email - a unique email address which can be deleted at will.
There were some technical challenges involved in the phone number idea. It would have meant routing a user's calls and texts in such a way that their Caller ID number was spoofed when connecting to someone who'd previously called or texted the temp number. Not insurmountable - but hard to explain to users. "Yes, if this guy texts you, you can text him back from a temp number."
There was also a small risk of fraud and abuse from people getting temporary numbers. Again, we could probably have developed something to unmask them if law enforcement required it.
And, there was a significant chance of numbers being recycled. I'm sure most of us have had the experience of someone calling for the last person to have our phone number.
Rather more significantly - dating sites hated the idea. It implied that all the men on their sites were horrible bastards who couldn't be trusted. It sent a signal that women were under threat from their users, and that wasn't good for business. There was, fairly, some pushback that this was victim blaming. It shouldn't be a user's responsibility to take technological measures to avoid harassment.
But, what finally stopped the idea was the prevalence of dual-SIM phones and cheap / free PAYG SIMs. It's easy to grab a cheap SIM for a couple of weeks and bin it when you're done. If you only use it for chatting with dates, you can dispose of it whenever you like. And if you like the guy, you can give them your "new" number.
I'd still like to be able to programmatically change my SIM's number. I'm sure Apple's eSIM probably lets you do something similar. But, for now, I can just order a free SIM and shove it in my second slot.
Oh well, plenty of other ideas left to change the world.