Hoe does not lose durability when used for non-farming activities

Breaking blocks also doesn't decrease the durability of hoes.

Hoes do no extra damage to mobs, nor do they speed up mining of any block, so this isn't a bug. It's as if you hit a mob with a torch, or your fist, etc.

Agreed, this is the same as bows not taking damage from melee or mining. I don't think it should be fixed, as it would be more of an annoyance.

If you argue that it should take damage simply because it has a durability bar, then fishing rods, carrots on sticks, flint and steel, and armor ought to take contact damage too. Heck, maybe even make weaker items such as sticks and torches get instantly destroyed when used on mobs or blocks. As I said, fixing this would serve as annoying, and nothing more.

Items will only take damage if they're used what they're intended for.