GDPR doesn't actually require cookie banners. If all the tracking and data protection you do is justified, justifiable and obviously necessary for the lowest-common-denominator service you provide, you don't even need to ask for consent (though do let your users know what's up, anyway, with at minimum a Privacy Notice in the footer, because that's just common decency).

If a company asks for GDPR consent, either:

• They have cool, optional features of their site / service / system (though they could just ask at run-time, when you try to use those features, in most cases); or

• They're doing something dodgy and want to wave a magic wand and remove the dodginess by getting you to “consent”.