I have trained in quite a bit of self defence with various different martial arts.
The hoe could be lethal in a very unlucky scenario, as you say, if it struck an exposed neck, or major artery. However it is a very ungainly weapon. It is significantly less dangerous than a knife, for example. Police in the UK are not equipped with guns, yet they deal with knife attacks all the time with just a baton.
It seems to me like the cops in the US are far too reliant on their firearms. Dealing with a poor weapon like a hoe should be quite easy to someone who is suitably trained. With all long weapons like this hoe, baseball bat, etc, anything that needs to be swung, you have to get in close, quickly. Then the assailant cannot hit you anymore. Then it should be quite straightforward to make the situation safe in a non lethal manner. This sort of response is completely ridiculous and should not be normalized.