Why is my $1600 iPhone 11 Pro Max only bring in $300 or 275 trade-in value when it’s in perfect shape and it has the maximum amount of memory

If you're not happy with the trade in offer, sell it outright and use the money for a new phone.

Or check with your carrier to see what kind of trade in offers they have.

The iPhone 11 Pro Max was release in 2019. It was discontinued in 2020. It is 4 year old tech, not 2 year old tech.

There have been 4 major versions since it was new.

Unfortunately you’re expecting a lot for an 11 Pro Max when we are now at the 15 series. Not realistic at all. You could likely get more selling it yourself but you still wouldn’t get anywhere near $800 for it. It was $1349 (or $1299 if you purchased from some retailers) when it came out back in 2019 for the 512 GB version (not sure why you would have paid $1600 unless you are including AppleCare coverage which doesn’t factor into the retail value of the phone since that was an optional add on you purchased. You’re expecting a lot for a device that came out over 4 years ago. Carrier trade in offers may be better if you’re ok with credits being spread out over 24-36 months. A well cared for Apple device tends to have the better resell value on average but when you let several upgrades come out the resell value and trade in value will take a hit. When a significant change (like the 15 series changing to USB-C for example) that value will likely see a bigger hit.

It is worth what a buyer is willing to pay for it. You are free to find another entity willing to purchase it for more. That's how a free market works. If Apple purchases it, they will most likely refurbish it to sell as out-of-warranty replacements. That's break-even at best for Apple. A person looking for a good deal on a used iPhone might be willing to pay more. Just be sure to make it ready for sale. See What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

Mobile phone technology is extremely competitive and moves very fast. Much faster than cars (which depreciate very quickly, especially luxury models). The four year old technology in your iPhone 11, while perfectly usable, is not worth much today when most carriers are giving away iPhone 14 models for free with a new contract.

It's only worth what it's worth. The value of technology decreases pretty much exponentially as new features and speeds are released; this is not surprising. To be fair, the phone is a sunk cost. Anything that you get his better than nothing.