You can choose which path (RPL->PPL or PPL only), further into your training if you want.
Generally schools will show costs to a RPL standard on the PPL path because you *do* have to be at the RPL skill standard at some point even if you don't do the flight test for the RPL or the exam so don't get an RPL. The training to that point is the same.
RPL == you can safely operate the aircraft as pilot in command - you need to reach this skill standard whether you obtain an actual RPL or not
PPL == you can navigate and operate in various airspace whilst flying the aircraft as pilot in command
By not getting an RPL you don't need the RPL flight test or exam.
Some people choose an RPL even if they are going to PPL because they want to take a passenger, are happy flying locally and want some tangible qualification at that point. Often they take a break in their training at this point as well.
Others just want to push through. You don't have to choose at the start.