Oh…good catch. I was not clear and I will edit my post.
The W9 is the minimum requirement that I tell my clients. I DO see the mucking/feeding positions as W2 employees where you dictate when and how duties must be done (as well as dictate the wage). I get push back (from clients) about the amount of turnover they have at these positions as well as the request of workers to be paid under the table. I do my best to inform and advise. I think this best fits the situation the OP asks about.
Farriers, vets, trainers, saddle fitters all fall under the “independent contractor” classification. They set their working times (appointments) and prices.