They definitely do not lay off 10% every year, knowing from personal experience.
It may not be 10% all in one shot, but these articles seem credible and also consistent with Glassdoor reviews, which also state Tesla does stack ranking.
I feel like it's common on HN for people to overstate their credentials, only to find out that they were like an intern or barely worked at a place for a year and then they talk like they're experts on a subject. At any rate, it's not that important either way, but I do find it interesting how decisive people can be on this site about things that are fairly easy to falsify.