because they use shitty frozen chickens and they cook them like 100 at a time and they only taste great because they are loaded roasted with chemicals/cheap ingredients. it's processed food, so it's cheap. the chickens use at the grocery store for roasting and like 5 bucks and then but 5 cents of crap on them and sell them for 10 bucks. it's also way more efficient to mass produce things than do them one at a time.

making your own chicken is more expensive because you're getting higher quality and fresher product and using highly quality ingredients. a decent whole 4lb whole chicken for me is 10-15 bucks, (20+ if you want a organic free range pasture bird) and I'm adding nice salt, nice olive oil, and fresh spices/citrus etc.

the home made bird is far healthier. but not as tasty because it's not loaded with crap.

To be fair, avocado toast is an actual scam and can be made home for cheap, while rotisserie chicken is legitimately expensive rn no matter how you get it.