Probably because the site author isn't taking the window.devicePixelRatio and backingStoreRatio when creating the 2D context.

> this "text" isn't in the DOM, it's not real text

The text is not in the DOM, but that doesn't mean it is not real text. It is text, literally strings, written with `context.fillText()` which could certainly be wrapped by screenreader software.

Doing so would make the world a better place for the bling by providing a more consistent experience - since 100% of people using canvas will never get extra budget to modify their logic, but 100% of canvas fillText() calls could be handled by a screen reader.

Unfortunately a great deal of engineers seem to have invested time and reputation in the unlikely change-the-world scenario, so I suspect blind people will continue to have a poor experience on the internet while a11y engineers who don't actually care for workable solutions continue to dominate the discussion.