If you've got manual door locks and manual windows, you don't have a locking tailgate so far as I know.
And for what it's worth, when I close my tailgate with the truck running, get back in and put it in gear...it locks all doors and the tailgate. I don't have to fumble in my pocket to dig out a key to lock it. In other words...my life is a lot easier.
I get wishing things didn't change. I'd prefer to have a manual transmission in all my vehicles. But because of the push toward automated controls in everything, it's no longer an option and I don't really have a choice anymore. Complaining about it doesn't do anything.