this is exactly what I had in mind when writing my comment. I'm on keto and I've fallen off numerous times in the past because it takes serious effort to maintain. The solution my wife and I have opted for is meal prep (cooking meals in batches) and buying in keto snacks in advance. If I find myself caught short and need to nip to the shops for food on the go, I'm usually restricted to one of 5-6 items in a moderately-sized shop. Even supermarkets might only contain 10 things I can have in the entire place. The dominance of carbs and sugar is truly mind-blowing.
If healthy diets were the default easy option and you had to go out of your way to get access to processed sugary foods, I suspect we'd see a drastically lower obesity rate.