Earlier quoted context omitted.
Looking up their patents ( https://patents.justia.com/assignee/e-ink-corporation?page=3... ), looks like their earliest patents are from 1998, so those should be expired already. That said, there's 36 pages of patents that seem related, so I'm sure that newly made e-ink technology will be covered by the newer patents.
It also takes time for manufacturers to design and produce. Even if someone had rushed out of the gate in 2018, they would probably not have ad products ready for a couple of years (and last year there was covid too) - and this with the most basic tech, which we know actually took significant time to be refined. I think a more realistic timeframe for usable eInk patents is 20 years from the first Kindle release, so 2…
It was a really hard problem that required totally different tooling from a normal display manufacturer so I'd absolutely expect that to be a huge source of delays in getting set up.
You can't just convert an existing display factory to make e-ink displays, so the startup costs are huge and the odds are good that you'll take at least a few years to work out the quirks. Probably more like 4-6... if you get lucky and can figure out what tools to use quickly.