Without entering the debate..........
If a pilot of a bizjet can't follow that process, that's negligence on their part. Whilst it is expensive (I think around 50K?) and it does take the plane out of service, if you can afford to own and maintain a biz jet, you can afford to upgrade to ADS-B.
I don't believe it is a matter of affordability or cost, rather that Service Bulletins are not yet available to install ADSB in many pre-existing aircraft types, including certain models of the Cessna Citation series.