alt Hacker NewsThere's no _need_ to use cookies for tracking purposes though, it's usually just easier/cheaper/quicker (or requested by the marketing department) to use off the shelf software than actually spend the time to implement these things.
But if you have a cart, you need a cookie banner regardless of any tracking you are doing.
Even the biggest tech companies, with surplus engineering resources, do third party integrations.
"easier / cheaper / quicker" means that will be the solution . You can't tell your boss "let's spend more money, more time, more risk" on getting it done.