I realize you aren't saying this, but note that while commissions are common among larger department stores, it doesn't hold true in general across specialist retailers that every staff member is on commission. For instance, if you go to a specialty cheese or wine shop, or a fishmonger or supplement store or even smaller local department stores, it's entirely possible to meet a sales clerk on commission, but it's also (perhaps more) likely that you won't.

Also, RE staff commissions -- this isn't always bad for the customer as some here are implying. Although there are stores where commissions can come directly from the manufacturer, or where some manufacturers offer staff commissions but some don't -- this tends to be bad, nearly always.

On the other hand, if the commission comes from the employer, this can incentivize staff to build deeper product knowledge and awareness of tradeoffs between different brands and products (not to mention: mindfulness of trends, customer feedback and return rates, etc), which IME leads to better service and better sales for everyone involved. I mean, yes, sure, it can also lead to employees simply parroting whatever they learned from the manufacturer brochure. YMMV

Brick & mortar retailers that don't provide commissions at all often still allow manufacturer led trainings of staff -- the retailer views this as essentially free staff development and morale building by increasing staff product knowledge while often providing free product or steep discounts. Sometimes manufacturers will straight up give away prizes unrelated to the products they sell (I've seen supplement vendors give away iPhones or cash prizes, for instance). Sales reps sometimes build personal relationships with certain retail workers they know have influence over purchasing or merchandising decisions. Often this is explicitly forbidden, but in practice virtually every company that has rules like this also rarely enforces them

In any case, my point is that commission structures do not imply that you're getting bad/misleading information from sales staff, and lack of commission structures don't mean that sales staff are free of undue influence from sales reps and manufacturers or that they otherwise aren't incentivized somehow to push a particular product on you.