Why do grandparents always overstep their boundaries?

So I currently still live with my parents. I’m saving toward moving out and I have been apartment searching. My son is 18 months. Earlier this morning, my son woke up a bit whiny. I cut him up some fruits while I washed dishes so I could make him breakfast. Now, my mom knows every morning he whines because he’s hungry considering he hadn’t eaten since the night before going to bed but I always soothe him with fruits before giving him his breakfast. I don’t just let him cry. For some reason this morning she decided to fuss at me as if I were the worse parent in the world telling me “You need to feed him as soon as he wakes up. No one wants to hear him fussing. That’s rude. He’s waking up the house.” As if she’s “grandmother knows best”. She was in her room, we were in the kitchen. She had no idea what the situation was but she got up as if she knew everything. While I washed dishes, he ate his fruit and that kept him quiet but she was over focused on the few seconds he wasn’t quiet and that didn’t even last long. She felt she had a right to tell me to use a different method. Feed him real food instead of fruit so he won’t be crying but he was fine just the way I did it but she made it up in her head that he wasn’t contrary to what I saw and know but I guess this is why I’m saving toward moving out.

Why do grandparents always overstep their boundaries?
Post Opinion