Other people in this thread report that Schwab pays interest on checking account balances. Schwab's website clearly states that their checking account accrues interest. There's a footnote link there, but the fine print simply says that the rate can change over time.
https://www.schwab.com/public/schwab/banking_lending/checkin...
Of course, just as I don't understand people using a traditional bank these days, I likewise don't understand letting a large cash balance sit in checking account. The best interest rate you're going to see these day is probably sub-1%.
So why leave excess money sitting around in a checking account, when sweeping it into even a short-term U.S. bond fund would provide 2x-10x the return with no additional risk? (i.e. if U.S. Treasuries default, then money market accounts are probably screwed too anyway)