Your car is shiny & clean. You take it to have it washed each week. The inside is vacuumed, the tires have armor-all. The windshield and windows are cleaned. You may even have one of those smelly things hanging somewhere.
The engine, a different story. Smoke pours out while driving down the road cause the oil hasn't been changed in probably a couple years. The oil filter is clogged & filthy.
The tires are good, but the steering wheel shakes and pulls cause it needs an alignment. When you turn the wheel you hear that awful sound cause the power steering fluid has leaked out.
Your brake pedal grinds cause the brake pads are gone. The engine runs hot cause the air filter looks like its' been playing in the mud. The battery cables are corroded.
Somebody looking to make a buck keeps giving you an inspection sticker each year.