My point was to contrast with
@clearstream's assertions about how it works.
clearstream was saying: the upshot of a Streetwise checks is "you are told such-and-such by a NPC" and now the GM is at liberty to decide whether or not what the NPC told you is true. clearstream began making this point a few pages upthread by picking up on my use of the phrase "rumour mill" and saying that rumours are per se not fully reliable.
I am saying that the upshot of a Streetwise check is not that you hear about something (rumours, information). It's that you
know a fact - who will sell you guns, who will sell you licences, where the dirt is, etc.
From the point of view of the character, of course, there is no difference between talking to a NPC and being lied to, or being given unreliable information, and talking to a NPC and coming to know a fact - it's all just talking and being told things. But from the point of view of the player - who is the one playing the game and making the roll for Streetwise - the difference is profound.
Streetwise in Classic Traveller is the earliest version I know, in a RPG, of a structure similar to Read a Sitch in Apocalypse World, which (on a success) allows the player to ask the GM questions from a list, like "which enemy is the biggest threat?" or "who's in control here?" As the rulebook explains to the GM (p 199), "sometimes you’ll already know the answers to these and sometimes you won’t. Either way, you do have to commit to the answers when you give them." The GM can't say so-and-so "seems" like they're in control, and then later on reveal that they really weren't.
Likewise in Classic Traveller Streetwise 1977. The GM can't say (on a success) "You hear a rumour that so-and-so will sell licences under the desk" and then reveal that to be a lie, or a false rumour. The player, on a success, gets knowledge of a fact about the fiction: so-and-so will sell licences under the desk.
That doesn't guarantee a licence, of course. It doesn't bypass the rules for NPC reactions and the way they interface with Bribery. Or if the player learns that the dirt is in a safe, that doesn't bypass the rules for Mechanical or Electronic or Demolition or whatever is appropriate to actually getting the safe open.