Banks don’t all offer API access in the USA. It’s getting better but can still be a mess of needing to use Plaid, Yodlee, screen scraping, etc… for bank data access.

Banks don't give out access to this API easily. Unfortunately it's not some OAuth thing that a new upstart accounting software could easily hook into, therefore the banks gate keep feeds to major accounting providers and no doubt charge excessively for the privelage. We need regulation to open feeds to anyone willing to consume them, or a bank to add it as a feature but why would they when they can charge Xero and MYOB to access proprietary feeds

They probably don’t want to deal with individual subscribers but if enough open source users wanted feeds you’d create a niche for a SaaS that does nothing but provide bank feeds for a few bucks a month. That’s the kind of micro SaaS one person could run.

There are some things that are “natural SaaS” and interoperability with ugly services run by huge banks that are probably moving targets and probably have administrative overhead to use is one example.

I haven't used it, but the team (person?) that makes Buckets (https://www.budgetwithbuckets.com) makes SimpleFIN (https://www.simplefin.org), which seems like it exposes exactly what you want: simple transaction data from arbitrary banks.

Plaid offers transactions APIs (https://plaid.com/products/transactions/), but I guess to your point these APIs are geared towards fintech companies, not personal use.

EDIT: I don't know how well it works in general, though. You'd have to test it yourself.

Fintable offers the service but it only interfaces with Airtable. You can easily download a csv from there, or use the Airtable API. It's not for those who don't want their data in the cloud, but I've found the service to be pretty good.