Because some 'picky eaters' are using it as a means of control.
#1: Every meal had to have no less than three items, not including salad, which was 'just a fucking garnish'. Egg & Chips was 'filth', but Sausage, egg & chips or Egg, chips & beans, Ham, Egg & Chips were all permissible. anything even slightly deviating from his norm was 'shit' and rejected. The plate of food tipped on the floor because it had Romanesco instead of standard Cauliflower was an example. As was throwing away an entire leg of lamb because there was a small piece of fat on somebody else's plate and the sandwiches snatched and thrown out of the window because one had a tiny section of the round bit of a tomato instead of just perfect slices. Chile con Carne was liked, but if it was with rice, it was binned due to the absence of chips. But chicken in sweet and sour sauce had to be with rice and at least half a jar of the sauce poured over the top. Highlight was going through the cupboards and throwing out tins of tuna, then binning all Scampi, wet fish and prawns because he didn't like it so wasn't 'going to allow it in the house'. Is now strangely 'allergic' to anything he doesn't want and wibbles about toxins and poisons in the things he is 'allergic' to, right up to the point at which he decides he isn't allergic (usually when he meets a new girlfriend).
#2: 'I don't eat Pki, Cn or Wg food'. This included garlic, ginger, chili, curry, Christmas cake once he realised that you put spices in it, pasta, rice, ginger cake only once his Mum slipped up and said the slices of 'cake' he'd been eating for 20 years were ginger cake, Chinese, fritters if you called them by a foreign name and barbecue lamb if it was put on a skewer to cook like in a kebab shop before removing the skewer to put it on a plate - would say how great it was if he hadn't seen a skewer involved. Had a tendency to roll in drunk eating a large Doner with garlic, lemon and extra hot chilli sauce and definitely came home with curry sauce down his shirt a couple of times.
3# Small child. Ate tomato at one meal, as had always happened. Next meal 'I don't like tomatoes'. Don't eat them then. 'I want a biscuit'. There aren't any. Next meal 'I don't like pasta'. Don't eat it then. 'I want a biscuit'. There aren't any. Next day (eats Broccoli regularly, friend at school says they don't like it) 'I don't like Broccoli'. Broccoli not put on plate. 'What's that? I don't like it'. How do you know you don't like it? Silence. 'Can I have a biscuit?'. There aren't any. 'I'm hungry. Can I have sweeties?'. There aren't any. There are yoghurts, though. 'But I want sweeties'. Would you like a biscuit? 'No. I don't like biscuits. I want sweeties'. We haven't got any. 'Can I have my lunch, then?' Yeah, fine, here you are. (eats tomatoes, pasta, cheese chunks and everything else, including taking some broccoli when offered).
4# What's that? (Chicken Goujons) Ewwwwwwww, don't like that. What's that? (Long Chicken Nuggets) Oh, I like chicken nuggets. None of that fancy muck, stick to what you know, that's what I always say. Would eat vast amounts of curry if led to believe that it came out of a jar instead of being made from fresh, including 'Bombay Potatoes' (otherwise known as Potato Curry, as it went nowhere near a packet of Schwartz). Threw a tantrum once because he was given a ham sandwich after declaring he 'wouldn't eat THAT muck' when pork with oven roasted Mediterranean vegetables was being prepared. Turned out that he wanted the nice food after all. Too late, sunshine, it's been eaten by less fussy people than you.
None of these people had ASD or any other diagnosed condition. Small child is allowed leeway, as peer influence is obviously playing a part. GM still described her as a picky eater who 'can only eat biscuits and sweets, the poor love'. But the adult males - it was absolutely about control (plus an element of racism) and wanting to be pandered to.