That's about to not be true. Atlas V + starliner has flown two people and has strap-on boosters, I think it only gets the rating once it returns from the test flight though.
The shuttle didn't have a propulsive launch abort system, and could only abort during a percentage of its launch. The performance quoted for starliner's abort motor is "one mile up, and one mile out" based on what the presenter said during the last launch. You're plenty safe as long as you don't intersect the SRB's plume.
Not that I think it's a good thing, but...
Its mind boggling that SLS still exists at all. At least $1B-$2B in costs whether you launch or not. A launch cadence measured in years. $2B-$4B if you actually launch it. And it doesn't even lift more than Starship, which is launching almost quarterly already. This before we even talk about reusability, or that a reusable Starship + Super Heavy launch would only use about $2M of propellent.
The safety posture of that whole program, for a US human space program, seemed bad. That they chose to use solid rocket motors shows that they were willing to compromise on human safety from the get-go. There are reasons there hasn't ever been even one other human-rated craft to use solid rocket motors.