Front-End interfaces can be as complex (or more complex) than Back-End/infra/analytics/etc... At the end of the day, it is all about data and the front-end needs to maintain state. If your interface is complex, your state will also be complex.
Theoretically - yes, practically, on average, any of the things you’ve listed is far, far, far more complex than your average frontend that is basically glue between “real” logic and user.
If you are doing CRUD simple data apps, I don’t get why your backend will be complicated. Sure the industry has complicated stuff (aws & friends) for complexity sake but that doesn’t mean you have to go down that rabbit hole.
Front-End is complex which is why we have 36362 libraries to solve the same problem and still move user interfaces sucks.
I'm not a fan of the "front vs back" dichotomy. Chrome is just another box as far as my responsibilities and goals are concerned, but it always feels like there's a mental handoff switching to this one context.
