I don't see the runes as anything but a bit of color for the wards. That is they aren't something the wards are anchored to. They're just part of the ward. Regardless, there are exceptions to the must have a threshold or couple other rare things rule for wards. So, if you want an exception for your wards, you should feel free to make one.
I do not see the locker as warded but as protected by a rune set to trigger off under certain circumstances. Although this sounds like semantics, the stories of "Something Borrowed" and "Even Hand" showed some very poignant examples of how Gard's magic is rune based. In other words anytime Gard "casts" a spell it requires a rune that is already pre-made with that particular usage in mind (kinda like a scroll in Diablo 1) in this case, the "scroll" was set on a metaphorical tripwire at the door. NOT a ward!
As to the Renta-storage unit, There is also the example of Elaine's ward on the hotel door. You can build wards on non-household thresholds, you just have a really poor anchor for them that severely limits what they can accomplish. Harry worked long and hard to reinforce that anchor point as much as he could with arcane drawings and runes and such to focus the wards (kinda like the runes on his staff and blasting rods help him focus his magic) and yet from what I remember (fuzzy) he still only had an early warning detection system out of the deal.
Yah he had a ward, but it wasn't going to liquefy several dozen zombies. It was much much much more limited than that.
these WoJ's allow for that
No wards on the office. You need a threshold for anything but teensy defenses, and the office is a public place of business, not a home.
No wards on the office. To build a ward, you have to use a threshold of some kind. (Well, you can use other kinds of similar energy structures, like ley lines, ogham stones, etc, but you can't just slap them down anywhere.) No wards on Harry's office in the books for that reason.
The office doesn't have a whole hell of a lot of "home" energy around it. Virtually none. I mean, a hotel room would have more. Harry could probably sling up some kind of tripwire-rings-a-bell equivalent ward, if he wanted to, but even that would be tricky and he has better ways to spend his time and effort.