As with most #brexit coverage, this is looked at almost entirely through the lens of British establishment. The views of the EU are only considered as a one sentence footnote in the second to last paragraph.

The UK can’t join the EU customs union because the EU doesn’t want them. The UK’s history as a wrecker, and their fervid rancid domestic politics, mean they can’t be trusted to honor any EU deals, so the EU is unlikely to make any. They made their bed, they have to lie in it.

Imagine if Starmer got access to the EU common market, then Farage became PM. Why would Brussels want to sign up to that?

England isn’t a world power, and they can’t make things happen by force of will the way influential world powers can. When they learn their place and apply for access to the EU in the usual way, they might gain some traction, but as long as their atttiude is, “We’ve decided we can do this so now it must happen,” the EU will string them out indefinitely, no decision, no deal.
https://aus.social/@oscarjiminy/115671539210059453