Those warnings and replacement schedules are calibrated for heavy use in a mission-critical office environment, where people are printing dozens to hundreds of pages an hour (depending on the specific model) all day, every day; and where any printer failure costs many thousands of dollars in direct and opportunity costs.

In a residential office with orders of magnitude less use, and very low costs for an unexpected failure, it'll probably work fine for many years.

tl;dr Used office-grade laser printers are often a great bargain for home use.