rokket, you ask "why don't wives understand?"
I can't answer the 'why', but I can give you a prime example.
A couple of years ago, a friend at my yacht club wanted me to build a model of her husband's tank for her to give to him as a Christmas gift. He'd been a tank commander of a British Centurian Mk 5 back in the 60's in Europe.
My wife got upset with me spending so much time and money building the tank. She kept on asking me, and couldn't figure out why, I didn't just patch up and old 1:35 remote control German, 1943 vintage, Pkfw IV Aus G that had been kicking around the house for several decades. In her mind, it was already built and just needed some minor repairs, and it was a tank, so......