Poor resale value was and is a deductible business loss if company owned or leased and is fully deductible from the company taxible bottomline. Not a personal loss! The loss cost me nothing personally! So is the cost of having a dealer service/repair business do any repairs needed deductible and that's why it done that way. A business isn't allowed to bill itself with an invoice for the labor or wages/cost to go get parts needed or the labor hours required to do repairs directly by invoice but outside vendor labor is billed by invoice and fully deductible. The required repair parts are always deductible. When your tax is 50% plus each year on profit made, it gets your attention real fast. Business owners, accountants, and CPA's know the rules and work with them. Hourly employees etc have no idea what's involved it running a successful business operation. All they care is that they get their paychecks!
Besides, an engineering office doesn't have grease monkeys like our forum yo yo and in perhaps dirty/grimey clothes standing around just waiting to fix a vehicle should it be required. An office is a dressup clean place not a wrench jerking greasiy/dirty back room or under construction area. Think about that next time you go to an office or place that is more professional than an automotive service garage! Perhaps at a dentist, a bank, an insurance office, or even to a doctor, let alone your favorite meat counter or the restaurant you frequent.
Backyard mechanics are the main ones doing their own repairs as they cannot get a tax advantage and are trying to save a buck by doing their own oil changes and various repairs to their vehicles. They can save money but doing the same actually costs a business money.
