Why Traveller is not a sandbox…

The term sandbox is a misnomer, all Traveller series are collaborative stories told outside the canon universe even when they're influenced by it. This is also how we did it before there was anything other than three little books, and for many of us this is how we've always done it. The GM and the players decided what to do and just did it. Sandbox is a trendy term right now in RPGs that describes what the hobby has been doing for 50 years.

As an example, when there were just three little black books there was still the social standing characteristic. It implied that your lineage affected your position in society and extended certain privileges. Of course we also had titles in the rules so people understood Traveller had assumed nobility in the setting. So while there were Dukes, Counts, and Knights we could decide from there. In many Traveller universes we cribbed ideas from elsewhere. So taking a clue from the British empire planets may have had viceroys as well as other nobility in planetary administration. We could also decide to use the terms Senator, Tribune, and Equite; basing the system on the Roman Republic. It was up to the GM and the crew.

There are always players and GMs who are intimidated by or are afraid of changing things. GMs even think it removes their power or control. If you only allow canon events and setting elements your players have no power, no agency, cannot effect any change, and may as well not even be there. Traveller isn’t a sandbox, it is your game.