In four years of marriage, DH and I have purchased four houses. Two for cash, two with mortgages. We also refinanced one rental property. OMG, in CA, they are all up in your Business! Each one was a different invasion of privacy. Yikes! We never intended to pay cash for our primary residence, but the bullshit just kept piling on. We findally looked at each other and said "Enough!" We paid cash and that was the end of that. We live in a HCOLA, had just sold two houses, so yeah, we wrote, er, procured a Cashier's Check for $928k. It was kinda crazy fun to do, but we still wish we'd grabbed some of that cheap mortgage money.
Here's an example: My brother was buying a house. On the day before closing, his lender started demanding tons of documentation that simply wasn't available. He called me, guessing I was sitting on a ton o' cash ;-)
I transferred the entire purchase price into his account the next morning. (We use the same bank.) A week later, I had all the money back. Months later, our mortgage lender just did.not.get.it. Wanted me to do tons of explanation, get a "Gift Letter", blah x3. Seems if you deviate a fraction of a degree from their definition of normal, they just freak out.
Interestingly, we were never asked about cars, but they're all older and paid for, so no recent transactions, I guess?