> they advertise one price but actually have tons of mandated fees when you show up to purchase
I had a similar experience booking a hotel room recently. Despite advertising a rate of $x, when I'd click through to complete the booking, towards the end of the process every single one would tack on a mandatory "service fee" of somewhere between $40-80. It seems to me to be a way to keep their room rates artificially lower to stay competitive on the price comparison websites.
(Maybe this has been a thing for a while - I haven't booked a hotel in years)