PDF, although it can resemble PostScript, is not PostScript. PostScript is a Forth-derived Turing-complete programming language that, in an era of generic printer drivers, offers little benefit anymore since it’s unlikely that an OS printer interface would take advantage of its capabilities. In the old days of programs managing printer output directly, it was handy to be able to do things like decompress TeX PK font bitmaps on the printer (or even more dramatically to send binary data for illustrations to be decoded and decompressed on the printer), but the set of printer primitives that are supported by OS printer APIs is constrained enough that nobody will do these sorts of things anymore. PDF is now essentially the lingua Franca of print interfaces and the programmability of PostScript is more a liability than a benefit.