Questions & Answers about Det är bättre för honom att du handlar.
Why do we use för honom here instead of till?
för expresses that a situation is in someone's interest or benefits them, like saying something is "good for" or "better for" someone. till is used when physically transferring or giving something to a recipient (like handing someone a gift), which isn't happening here.
Could we use åt honom in this sentence instead?
Not without changing the structure and meaning! bättre för honom means the situation is better for his well-being. If you used åt, it would need to attach to the verb handlar to mean doing a chore on someone's behalf: Det är bättre att du handlar åt honom (It is better that you shop for him).
Why use the verb handlar instead of köper?
handlar refers to the general activity of shopping or running errands (especially for groceries). köper translates strictly to "to buy" and typically requires a direct object because you have to state what you are buying. Since the sentence focuses on the general chore of shopping, handlar is the natural choice.
Can I drop the word att like we sometimes drop "that" in English?