Because Sara Lyons is still alive. In fact, her possibly being killed by the Vault Droid might be a fanon theory to why Maxon has such hatred of Synths.
- Zigzagged: Season 3 does take place before Fallout 4, but Sara Lyons survives the battle with the Vault-Droid. However, Season 4 is more or less concurrent with Fallout 4, taking place around the time Maxon brings the Brotherhood to the Commonwealth aboard the Prydwin.
A popular bit of fanon has it that the Storyteller is actually the protagonist of Fallout 3. He is intimately familiar with the Capital Wasteland, is a member of good standing with the Brotherhood of Steel (as the Lone Wanderer would be by the end of Broken Steel) but apparently outside of their standard command structure and apparently knows Sarah Lyons well enough to cash in favors.
- Jossed, as The Storyteller, in one of the early Season 3 episodes, mentions meeting Tandi 40 years ago, meaning The Storyteller is at least over 40, while the Lone Wanderer would be 25 around 2283 (assumed time Fallout Lore takes place.
When telling the story of fallout 2 he mentions a brotherhood paladin and keeps pointing out how rugedly handsome he was.