Well not exactly earning calls in the classical sense, but haven't you heard about these startups announcing how they have scaled to $100 million in 3 months etc. Maybe revenue calls every quarter.

All the public ones?

I'd say at that point they are no longer startups, they've already started up

Lots of businesses like to claim being a "startup" as it brings connotations of innovation, dynamism, coolness, being the "next big thing" etc. There are many senses of the word, and it can be used in different ways (e.g. I work at a small business which has some elements of startup culture, and it's not an incorrect way to give people a sense of what it's like here - but we're definitely well established) but I think often being one of the "cool kids" is part of the motivation.

I would say in the AI age almost every business is a startup as per PGs definition [https://paulgraham.com/growth.html]