I know this is lacking in neighbourly spirit, my elderly neighbour (80's) always expects me to do her lawn, I offered to do if for her when we moved in over a year ago because it was getting long, and now she just expects that I will do hers whenever I do mine.
She has three sons, and at least one grandson who stays with her a lot who is over 16, who could do it, and it's not like she doesn't have a lawn mower, but still expects me to use my tiny little thing
I have been doing this over a year now and I have suffered with depression in that time so even doing my own lawn was a struggle and was left until it was overgrown before I did something about it. most of the time hers was left until it had got so bad before I had to do it again, and if i didnt do it she would get a man to come around and cut it and complain about the price.
I even end up using my own electricity