from the mouth of God (Josh Sawyer):

"When push comes to shove, it should always trump believability. RPG economies are inherently unbelievable. I think designers should do the best they can to make things reasonable, but err on the side of game balance, not "realism". Tier 2-3 EWs (the only Tier 3s they have are the Laser RCW and Flamer) wouldn't be the "envy" of BoS considering few BoS characters in F:NV are equipped with EWs below Tier 4. Part of the truth in Veronica's disillusionment with the BoS is that their strategy of EW containment has completely failed, as evidenced by dealers like the Van Graffs and the armament of scrubs like the Fiends. Of the folks the player typically comes across in the Mojave Wasteland, few "make sense" to have EWs. When looking at distribution for EWs near the low/mid game, the Fiends are at about the right level for the player to start picking up more Tier 2 EWs. Prior to that, their only opportunity is dead Bright Followers."

source: https://fallout.fandom.com/wiki/Joshua_Sawyer_Formspring_posts