One of the things which makes worldbuilding believable to me, in certain settings, is inconsistency. I don't believe in one planet with a single culture. In many settings, I find it implausible for a town to have a single culture. Often a mixture of levels of technology is much more believable and likely than, say, everything being done by sophisticated nanotech.

Yes, this! My go-to favourite worldbuilders (and all-time favourite authors since my teenage years) are Diana Wynne Jones, Kate Elliott, Karin Lowachee and Sean Stewart. They immerse you in worlds where there are multiple cultures, and even within a culture, individual characters have different viewpoints, desires and traditions. There is cooperating or clashing or both. A world or setting where all the people were the same or all wanted and believed the same things would feel very thin to me. (Lois Lowry played off this idea very effectively in her excellent 'The Giver!')

I love what you say about things going wrong and people screwing up, and about food. Yes!! Along those lines, also: clothes, and music or dance, and language, and mythology and spirituality and history!

These are a few of my favourite things! ;)