We first added explicit support for payware in TS2009 SP3. This service pack introduced the concept of activating individual JA files through separate serial numbers. This was always a stopgap solution; there are practical limits to how many products we can support with this technique and it's not a particularly easy process for developers to build the package or users to install the package. The EXE installers are not cross-platform, and each EXE installer needs its own maintenance and patches. They also do nothing to discourage piracy, and can't be purchased/installed without leaving the game environment.
We first added in-game payware in Trainz Simulator iPad. This introduced the ability to purchase and activate content within the game, but wasn't yet ready for third-party payware content. The iOS platform has some significant differences to how things are done on the PC, so it's not a simple matter of taking some PC-developed payware content and bundling it up for distribution. There are also differences in user expectations between the Windows version and our iOS user-base.
Finally, TS12 SP1 adds the ability to install third-party DLC. Instead of bundling individual items into large JA files with an EXE installer and a serial key, or instead of distributing payware as simple unprotected CDP content archives, we can now deliver third-party payware content directly to the end-user. This gives us a lot of options, and hopefully will give our affiliated third-party content creators a lot of opportunities. There's still a fair bit of work involved on our end to QA and package the individual items, but we're in a lot better position than we were when everything was a JA file.
In terms of the privileges container, I shouldn't need to point out that anybody with a text editor can overcome that "protection".