There's a broad, ill-defined spectrum between plagiarism and homage, between being x-ish and "ripping off". Nobody's fooled by these logos, but we're not meant to be: the logos are saying that the shop sells fried chicken of a vaguely KFC-ish nature, which is what we're looking for on a Friday night, and the logos do that by being vaguely KFC-ish themselves.
It's not a question of 'ripping off', except perhaps in the sullen way those who employ an attack-lawyer resent anyone doing anything that resembles what they do, just because they've decided that they 'own' the idea of fried chicken on the High Street, say.
These logos are KFC-ish more than they are Nando-ish, more than they would be, say, Forest-of-Dean Traditional Microwaved Chicken-ish, and much more than they are Father Christmas-ish. That's all that's meant by being KFC-ish; nobody except attack-lawyers cares about the degree of resemblance.