Those really expensive brands like Bentley or Diro don't expect Amelia's follower to actually buy anything (although I feel like it is getting increasingly more "normal" to save and save or go into debt for that one Chanel purse), this is just a branding strategy. It's normal advertising, they want to put their name out there, show that they're "cool" and in with the crowd. A lot of these high fashion brands I'd argue ten years ago were almost like "old lady" or actually unaffordable, unattainable brands in a way, you barely ever saw them on anyone except you've been moving in circles that can afford them anyway. Now they are in practically every time line, every vlog, their name is out there, they are being talked about (exibit A, just now). Social media has opened up a whole new world for them to advertise to and to make them even almost "relatable". Do you think those freebies to influencers cost them anything? That they pay Amelia a lousy fee to drive around in their car for a day? A Dior bag is just made of some fabric in the end (not bashing the design that goes into it but let's be real, it's a bunch of fabric and hardware and to fabricate one of them is extremely low price, especially in comparison for what they sell them). It is mainly to create brand awareness for the followers to recognize their name and connect it with high class stuff so in case they do have the cash lying around or they want to splurge on something they remember, hei, there was this fancy brand with the nice stuff, let's see what they have.
Also the swipe ups, as far as I know, make the website remember who sent you there. So let's assume you swipe up, check out the website, find something nice, maybe even affordable. A scarf, a pinky ring for 200 pounds. You bookmark it. A couple months from now you get engaged, you get a promotion, whatever, you want to treat yourself. You go back to the site and wouldn't you know it, actually buy the thing. Guess who still gets money from this purchase? Amelia, because this site remembers where that first affiliate link came from. That's why she'll never tag the brand in an instagram post. If someone asks where this and that is from, she'll just be like: "Hei, I linked it under the pic <3", or whatever.