Why do we need to keep accepting cookies (almost) every time we visit a website. It is the law that any website must get the users permission before storing a cookie in their browser, but most implementations seem to be broken and you end up getting asked to allow it every single time you visit the site. Why isn't a cookie stored to remember your cookie preference? Then there's the websites which seem to be completely over the top with pages of options you must read through before you are allowed to continue (these are probably the sites that are using them for bad though).
Most people don't know or care what a cookie is and just accept them anyway as soon as they see the pop-up or banner. A lot of the people who do care about it end up with the wrong idea that a cookie is a bad thing that tracks you online and steals your personal data.
Basically a cookie is just a way for a website to store a piece of information which can be used to make your use of the site easier or more customisable. A login session ID is a common cookie which can be used so you don't have to keep logging into the website every time you open your browser. Other cookies could be used to just store your timezone or your theme preferences. All this stuff could be done without using cookies but then websites would not be able to be personalised for your account without getting all your preferences from the server all the time which could just slow things down.
Just like with all tools, bad people can use them for bad things. This is where the online tracking problem comes from - because people wanted to spy more on their users, not because cookies wanted to track you. This led to most people thinking cookies are just bad things.
We don't have to listen to warnings about scam calls every time we answer a phone call, and the cashier at the shop doesn't need to explain to us the dangers of letting babies play with plastic bags before giving us one. So why do we have to see a warning about cookies on almost every website we visit daily?