Electronic books that don’t balance to the cent are defective.

I’ve certainly seen lax accounting and reconciliation practices in businesses such as those you describe but it’s absolutely not been the norm in my experience.

Individual books, yes (though I am still very dubious of the value in doing this given the guarantees that modern computers/databases offer). I'm talking specifically about cross-department reconciliation where different departments are keeping their own books and have their own data pipelines/etc. They absolutely still have to be reconciled, but there is no expectation of an exact match from the SEC or internal/external auditors.