You could do user agent sniffing and skip showing the banner if you know the browser supports cookie purposes.

Of course user agent sniffing tends to cause a lot of problems, so this probably isn't a good idea.

Yes it would require everyone to make changes, but like the other person who responded to your comment it probably wouldn't need to happen at the same time. The point being is that it's probably a bit late now but if this was the original solution proposed by the EU the end result would be a lot cleaner while still taking about the same amount of effort (at the end of the day web developers still had to look at all the cookies they set, categorise them, implement warning banners and then correctly handle responses.