I am aware that WY Metro know there's an issue with the companion bus passes as if you request they will issue you a duplicate normal disabled pass for use outside of the WY Metro area where a companion is not valid and these passes tend to work a lot better around the country
Two issues with that:
1. As Deerfold says, it limits who your companion can be to a single person whereas with the normal method it can be anyone who is available (family member, friend or even professional carer depending on what you are doing or who is available) so it is more restrictive on the disabled person.
2. Issuing a separate card means you are issues a disabled pass to a person who isn't disabled without any tie to the purpose of the card (acting as a companion) meaning an able bodied person can travel for free wherever they want within the national criteria even without the person who needs assistance so the "companion" has less restrictions. The point of a companion entitlement is because a disabled person cannot travel without assistance so the disabled person is travelling for the same cost of another disabled person, not to save someone else money generally because they sometimes travel with a disabled person who needs assistance.
Companion entitlements are a local enhancement, which means they only apply within the area agreement of the local authority who issued it (which may allow cross boundary travel if there is an existing agreement between neighbouring authorities), and who qualifies (if anyone) and how they are issued varies from one authority to another. One authority trying to get around this convention by issuing a pass to people who don't qualify for one hardly seems fair. You may feel that companion entitlements should be standardised and made available nationally but that doesn't seem the way to do it - many years ago I knew of a bus driver who had a companion entitled bus pass and was caught using it to give their friends free travel as their "companion" whilst they were on duty driving the bus (it would be easy to see someone selling the companion entitlement if it was a separate card untied to their travel on the basis that the value to someone who travelled regularly could be higher than what their companion would pay in bus fares for their own occasional use so they would make a profit selling the card and paying fares when needed).