Do accountants who are preparing business taxes really do adjusting journal entries for everything from payroll payable to prepaid insurance to interest payable, etc.

It seems like what I learn about accounting in classes is not what is really done in business accounting in reality. I see accountants do some adjusting entries like for accumulated depreciation, but not the categories I mentioned above. Does anyone do accounting the "proper" way? If not the accountant, who else is going to get businesses to have correct financial statements?

Keeping a set of books and preparing a tax return are two different processes. Journal entries are prepared to provide a set of books for audit and preparation of the financial statements. All journals made have detailed working papers associated with them. The accounts are then used to prepare a tax return with appropriate adjustments according to tax allowances and rules. It is possible to take a set of books kept on a cash basis and make adjustments to prepare financial statements on an accrual basis, but in a complex organisation this can lead to mistakes so better to maintain the detailed process. What you learn is only a microcosm of all the adjustments needed at balance date