I have an XR7 Taxi, The one I have is one of the games on the above list, sold originally through Eastern Music (kinda neat to know how the machine started out). I will mention that the XR7 is NOT on the front edge of my playfield, so, not all of these early diamond plate games had this marking. And from the looks of your playfield it does look like it might be one. Mine also has a few chipped inserts like yours. The colors on your look great. It would be extremely rare to find a Taxi with color like this that is not an XR7 playfield, or a replacement playfield. And with the chipping it isn't a replacement PF.

I picked my game up from an operator probably 15-20 years back. heavily routed and missing parts, one step from being totally parted out. It was left for dead. I didn't pay a lot for it back then, but didn't know how clean the PF was until I got it home. It came with 4-5 other pins in a lot purchase.
My point here. These games were all routed to see how they would hold up, they were test games that were testing the durability of this new clearcoat. And all routed heavily. It is possible that sometime in it's life a person had 2 taxi's, one with a good cabinet and one with a good (XR7)playfield. Possibly he swapped the XR7 out of the original cabinet to make one really nice machine and one beater or parts machine.