Yes I get that she may have been cut off from her family by someone, but why can't people in an ECV just be nice and say "could you get out of my way" instead of leaning on the horn.
Something else to remember is that those of us with wheels are at "hiney height." I am a full time manual/power wheelchair user, and I say "excuse me" politely 3 times to a person before I am more forceful and just tell them to MOVE! I am speaking generally to their rear ends, so in a crowded park with lots of noise, it is often difficult for them to hear me. This is another reason a person wheeling through a park may seem "rude." People may not have heard the polite requests...