When I worked at Bloomingdale’s they worked on commission, I assume it is still the case, but it might have changed. If they now get an hourly wage, it still would also be supplemented by commissions or bonuses of some sort. Saks and Nordstroms likely also have at least part of the pay tied to sales if not all.
Personal shoppers have the advantage of being referred customers, their clients tend to be higher price point clients, they usually have more flexibitlity with their hours and they shop the entire store for a customer without obligation to being present in a department for floor coverage. Their disadvantage is they don’t get to benefit from walk in store traffic, they have to be proactive in getting and maintaining clients. When I worked retail in Boca Raton personal shoppers usually made between $40k and $70k depending on the store and their skill. They can make more.
Anyone can use the service, you don’t have to be buying Armani and Chanel. If you already know the items you need you can give them a list and they can ring it all up for you at their register and it all gets done for you without having to walk all over the store, they do the walking for you.
For men who don’t like to shop I think it is a great service. The personal shopper will have everything already pulled in their size, coordinating outfits, all accessories, even cologne and the gifts he needs to buy for his wife or staff.
No tips at department stores, it usually is a store policy, but a surprise gift every so often was nice from our best clients. A tin of cookies, chocolates, that sort of thing we received now and then.