Is this considered common courtesy or not?

i live in a duplex and my neighbors hardly ever park on their side of the street. we each have room in front of our side of the house but they just love parking on our side and sometimes they'll even park across the street in front of someone else's house. it gets to be annoying when we have people over and they have to park farther down, especially my grandma who is disabled. tonight my mom was outside and i was just about to move my car and park it on the street when my neighbor decided to park there. my mom was telling her she was just going to park there and basically just bringing up that she never parks on her side. my neighbor kept saying that it's just a street and it doesn't matter where you park but then my mom piped in and said that it's common courtesy. in my opinion, i do think it's kind of rude of them to just always park in front of our side when they have plenty of room and i'm sure the other neighbors don't like it when they park in front of their house on their side of the street either. do you think it's common courtesy to just park in front of where you live? my mom told her she's going to call the landlord about it and the neighbor said that he's just gunna tell her to park farther down the street. i don't really know what he will say about the situation, but i'm pretty sure she's allowed to park in front of our house so, it'll probably keep happening. right? or no?