I think the difference is that food companies use those tricks in advertising and no matter how great it looks in a commercial everyone knows that if you order the same dish st the restaurant it isn’t going to look like that. On instagram the photos are thought to be more realistic because they are assumed to have been taken by someone just like you. It’s the difference between watching a commercial in which an actor/celebrity/spokesperson says that the food here is amazing! Every dish is perfectly prepared! You will love eating here! And a friend saying the same thing. The commercial is probably lying. It might not be. The food there might actually be just as good as the commercial says but you know that there is a good chance it’s not. You believe your friend though, because why would they lie? People know that food can be made to look better than it actually does, they just might not necessarily associate those techniques with instagram photos. This attitude partly exists because many users honestly just take a photo of their food on their phone and post it without spending hours with lighting and filters and such. If you are looking for the use of the techniques you will see them, but not everyone thinks to look.