I can't 100% swear to it but I think the postage meter standards in the US are completely owned by the postage meter vendor (Pitney Bowes) and not specified by USPS. These aren't actually "stamps" proper but meter tape. The meter vendor is on the hook to furnish the validation equipment to USPS, so it's all a closed ecosystem to them.
USPS seems to be lax on postage issues... at least some years ago there was some reporting that they very rarely actually scan (and thus mark as used) meter stamps and so you can get away with using them multiple times in practice. I think this is just because of not wanting to spend the money to install the meter validation equipment on sorting machines, since they already have the IMB to use for routing. I suspect they just don't see a lot of actual issues with counterfeiting
Pitney Bowes is much of what I call the "postal industrial complex" - large aspects of USPS technology are completely contracted to Pitney Bowes and a few other companies like Endicia. Pretty much every form of "electronic postage" in the US, including purchased directly from USPS, is managed by Pitney Bowes or Endicia, not USPS (Post Offices used to use an Endicia product for shipping postage, not sure if they still do).
USPS seems to be lax on postage issues... at least some years ago there was some reporting that they very rarely actually scan (and thus mark as used) meter stamps and so you can get away with using them multiple times in practice. I think this is just because of not wanting to spend the money to install the meter validation equipment on sorting machines, since they already have the IMB to use for routing. I suspect they just don't see a lot of actual issues with counterfeiting
Pitney Bowes is much of what I call the "postal industrial complex" - large aspects of USPS technology are completely contracted to Pitney Bowes and a few other companies like Endicia. Pretty much every form of "electronic postage" in the US, including purchased directly from USPS, is managed by Pitney Bowes or Endicia, not USPS (Post Offices used to use an Endicia product for shipping postage, not sure if they still do).