Lobby your lawmakers. Banks have no incentive to provide open APIs.
For example, in the UK banks did nothing until they were forced to - the market regulator now requires the nine largest banks to provide an open API (https://www.openbanking.org.uk).
The law doesn't restrict the banks giving access to non-AISPs and, like you say, many of the modern banks do have personal API access, it just sets a minimum bar you have to reach before they're forced to let you in. It seems like a pragmatic middle ground.
What is bad, in my eyes, is the law currently only applies to the CMA9.
In fact I randomly came across me bemoaning this fact 5 years ago lol . Also at one point I wrote my own small wrapper to access parts of their internal API  but I haven't touched that in years so I seriously doubt it still works at all.
I suspected it might be different elsewhere, but I had no idea that the situation was so dire that you had to actively go looking for a bank with an API.
 https://de.wikipedia.org/wiki/Financial_Transaction_Services (German)
 https://de.wikipedia.org/wiki/Homebanking_Computer_Interface (German)
It merely provides a standardized interface to access account data or initiate transactions, but it still uses a plain username/password login to authenticate.
Even that it does not do particularly well – the protocol is horrendously outdated and does not support "recent" inventions like credit cards on many popular banks, which means that banking aggregators have to fall back to screenscraping anyway.
However, this will hopefully change soon with PSD2/SCA, which does mandate such secure account access (based on OAuth2, if I understand it correctly).
I'm not currently aware of a US bank equivalent
In practice, banks never tell you the address of their OFX server and you have to rely on community compiled database (eg ofxhome); many banks' implementations are iffy; some banks even charge you for enabling OFX support on your account. In the end it's just so much easier to outsource this to Plaid, which is why they are a billion dollar business.
"Bank syncing is a critical feature that is coming soon!"
You can manually import QFX/other standard formats though, but not all banks have exports of this, and it's very manual.
I'm thinking of something where you download your statement (usually available in PDF form) and then drag it to a web interface where it then gets OCR'd and processed.
A bit more manual, but the upside is you're not leaking your creds and you should also have access to more data (banks have to provide statements and they usual provide them going back many years).
It uses Plaid out-of-the-box, but it has a pluggable provider model for other data sources: https://github.com/kevinschaich/mintable/blob/master/docs/PR...
In the absence of APIs from most banks, it would be nice if there was a client side personal finance web app that allowed uploading .csv or pdf statements, and scraped those for you locally, perhaps with the option of using your own Google Drive or Dropbox as a persistent storage backend beyond browser localstorage.
there are a few issues though:
1. some banks only send notifications for transactions that are over a certain amount (eg BofA is >$25)
2. the merchant name is arbitrarily cut-off (based on char length), so you don't really get reliable merchant info