Honestly the biggest problem was not that I wasn't shown the interest rate, but that they carefully avoided any financial talk (I never actually saw the final price of the vehicle, only the monthly payment and only learned the exact details, including the several extra thousand dollars of extended service plans when I was going to refinance the loan at my bank) and carefully flipped through the paperwork to encourage jumping straight to signing without reading, even joking "oh no you don't want to read that" at one stage

Every car I've bought since I've been extremely diligent to read through all of the paperwork before signing anything, and one of the times caught the permission to sell data for marketing purposes form which I declined (the salesperson seemed surprised when I spotted that one and said "oh that looks like one to decline")