The developers receive hundreds of suggestions a month. It’s just too difficult to add every suggestion inside of Robloxia Prison. The developers go by plurality, and majority voting.
In essence, they add suggestions that majority of the community want to be added in Robloxia Prison, however, there could be other reasons why it wasn’t added:
The feature is not entirely supported, or physically possible to implement on Roblox
The feature is too complicated to be implemented at this time
It’s not currently on the developer roadmap
Please do not feel discouraged if your feature/suggestion was not implemented.