Many people get their caravan/motorhome for short trips/family holidays and then consider a 'big trip' at a later date. These people would use RVWIFI for lower upfront and ongoing costs, and then might add the Starlink later depending on the plan for their trip, for them they would add the Starlink LAN ethernet port to the RVWIFI WAN port and they can get the best of both worlds. This also helps them avoid having to program new Wi-Fi into devices such as smart TV's so is more convenient, this is what Starlink ready means.
It's worth noting 5G is cheaper, faster and has lower latency than Starlink.. and Starlink has awesome coverage so it's about everyone's circumstances.