Those are really high resale prices. Not sure what's going on in Canada but with the high miles those prices are way out of line. I love my 2015 Double cab V6 4X4 but I would say even with the low miles I have of 24K it's probably worth 28-30k US dollars.
Sounds to me like maybe something is loose. I also have a 2015 and never hear anything from my brakes. Did you specifically ask the dealer to check the rear brakes for noise or just assume they would check them during normal service?
My 2015 tacoma 4x4 v6 fuel pump didn't shut off when the ignition was turned off. I didn't notice it until late last night when I went outside and heard a humming sound near my truck. It had been about 8 hours since I parked it when I discovered it. I turned the ignition on and it went silent...
If it were a new truck or low miles I would be upset about rattles. But, older high miles who cares. It's a truck and not a Cadillac. I personally would not care and just turn the radio up a bit. I know, not helping, sorry.