Once upon a time, one could say that one is vegan for health reasons or ecological reasons but now, one is not technically a vegan unless it is for the animals.
I don't agree with this, although it depends whose definition you use. I think if you don't use animal products you are a vegan, regardless of reason.
However...then again.... vegan is defined quite strictly, with the majority of vegans including the UK vegan society believing that you shouldn't call yourself vegan if you say eat cake at a birthday party or eat non-vegan pastas and breads.
Now, if you really are a health or environment vegan, and not an ethical vegan, then why would you care about tiny amounts of animal products in processed foods or whether some beer is vegan or not. It doesn't matter from a health or environment perspective. So, presumably, in practice health and environment vegans are not that strict about it, which in the opinion of the majority of vegans including the UK vegan society, does not make them vegan at all.
Also, if you are a health or environment vegan, you wouldn't have any reason to avoid non-vegan clothes and other non-food products, which, according to most, makes you either not vegan or "dietary vegan" or "plant based" or whatever.
However if you are health and environment vegan, but don't care about animal ethics, but do strictly avoid processed food with tiny traces of animal products and avoid non-vegan clothes and other non-vegan products, perhaps because you are just following along with your other vegan friends or whatever other reason you chose to be strict about it, then you are just as vegan as anyone.
None of the above is my opinion. I'm just describing how it seems that the majority of vegans and the UK vegan society sees it. Personally I think that the environment and health vegans should be welcomed more uniformly and clearly and compassionately. I think those looking to tighten up the definition are making a strategic mistake that may even lead to less veganism. Personally, I would like to see a simpler definition prevailing either: "Vegans do not use animal products" or "vegans do not use animal products as far as possible and practical". And I think the interpretation of that definition should be loosened up a little.