No, papers are not developer incorporated anymore... The last one was Kodak Polycontrast rapid III from the '90s... It was developer incorporated so when the paper hit the activator (a strong lye based alkaline solution), the image would develop in a split second, followed by a strong stop bath dip, then into a stabilizer or rapid fix, then a rinse in the processor...

The reason some papers print faster than others is like film... They have larger grains that are much faster/sensitive than other types... RC was made for rapid access printing where the exposure time was as short as possible for machine processing, for news, graphic arts etc... (I made 10's of thousands of processor prints in commercial photo labs, but now process is obsolete as no developer incorporated papers any more...)

Fun fact/ Colder tone papers are faster, even in FB as the paper grains are bigger/faster and make a deeper Dmax, warm tone papers are slower and the smaller grains below a certain size start reflecting different wavelengths of light color starting from black to blue, green to smaller grain mixes to sepia, yellow and smallest reds... Reductive toning shrinks grains to these sizes, additive toning adds smaller metals that reflect secondary wavelengths of color on top of the silver image...

Steve K