Thats because natural language is ambiguous. Even simple sentences like " I saw a man on the hill with a telescope" have multiple meanings.

This isn't solved by magic, but pure statistics. Try and ask your friends who has the telescope in the previous sentence and some will say the man and some will say "I". Without context we can't tell, but we can judge which one is more likely given who had the item in previous sentences of similar structure (the prior). Then usually we also have some context.

Now we can add context: "I got a telescope for my birthday and was eager to use it. The next day I saw a man on the hill with my telescope". Now most people would expect the speaker to be looking through the telescope, but the man might have stolen it and taken it to the hill. Even humans have to guess.