You and I have very different definitions of the word "simply".
Arranging proper backups at all is not something to take for granted when you're dealing with small businesses that have many other things to do, but obviously they're important for safeguarding the provision of products and services to all customers and it's important that any backups that are made are handled with proper regard to both security and integrity.
Requiring businesses to separate every tiny item of data that might ever be legally required from every tiny item of data that is collected and used with consent for reasonable purposes, just in case some customer one day decides to retrospectively withdraw their consent for some or all of that data, could easily become absurdly disproportionate. I hope it would go without saying that incentivizing businesses not to keep backups of all important data because of the compliance overheads is insane.
However, without such fine-grained separation, two weeks might be far too short a period to keep backups. To use my own businesses as an example here, we have accounting and reporting obligations that potentially require several years of data. The reporting information is typically derived once a year during reporting season, from straightforward records kept in the main databases and/or spreadsheets. However, we would probably have to completely restructure those records and denormalize all kinds of things in order to delete everything we don't strictly need for some legal purpose, which would be a huge amount of work.
That's just the structure of the original data. Then you have to consider things like deduplication in online backup services, where it's practically impossible to guarantee the complete destruction of all instances of certain data without destroying all backups that ever involved that data and starting over.
If this is the situation for small businesses that typically only collect a small amount of personal data in the first place and for obvious and necessary purposes, I shudder to think of the implications for organisations that actually process personal data as part of their main purpose rather than incidentally. I'm not sure it's reasonable to assume, in general, that it would even be possible to totally separate legally required data from everything else in such organisations, and there would surely be a lot of grey areas.
Now, please don't misunderstand me. I'm all for reasonable regulation to protect individuals from exploitation. I'm a privacy and civil liberties advocate, and I run my own businesses the way I hope others would run theirs, even if sometimes that means not doing things that would probably make us more money because they also make us feel uncomfortable. But there has to be a sensible balance, and the EU does not have a good track record of balancing its business regulations sensibly. (See also: EU VAT, cookie law, various provisions in the last round of consumer protection rules, etc.)