That’s because it isn’t a “negotiated” motability deal, it’s a branded (Go Charge) Paua card. Paua offer cards to businesses for their staff, they are actually really good as a company at getting providers onboard, but they don’t seek any discounts.
The win for Motability customers is seen as ease of use, no pre-auth and wide acceptance across UK & Europe.
I used it at some sites where my Electroverse card wouldn’t work, painless & the data provided by email after the charge is excellent (as it would need to be to allow business users to claim their charging back from their employers).
In life, it's not who you know that's important, it's how your wife found out.