There are exemptions for strictly necessary cookies, in which case explicit user consent isn't required. However, you still have to inform users about these cookies.

The question is, though, what constitutes strictly necessary cookies in which use case. It also isn't clearly stated anywhere - or otherwise agreed upon, in which way you have to inform your users about these cookies.

Hence, many website providers opt for the legally-safest, but terrible in terms of UX, alternative of displaying a cookie banner.