Then again... Book try to simplify things on several locations (which ironically just make it more complicated to read and understand). Take the running charge modifier for example. Running cause -2 modifier on all your actions (except the sprinting action). Charge an enemy with a melee weapon give you +4 modifier. Instead they "simplify" it and state that a charge attack give you a +2 modifier.
Same thing with SS. If shooting a SS weapon only as a simple action does not cause recoil to carry over and since you can not shoot a SS weapon twice in an action phase or take a complex action to fire a SS weapon they might as well "simplify" things and state that shooting SS does not (never) cause recoil to carry over.
That does not mean that shooting SA in a simple action would or would not cause recoil to carry over. But it does mean that SA can not be worded the same way since you can also fire SA in a complex action (SA Burst) which will cause recoil to carry over no matter how you read the text.
It all boils down to how you interpretate this sentence on p.175 Progressive Recoil
"Recoil penalties are cumulative over every Action Phase and Combat Turn unless the character takes, or is forced into, an action other than shooting for an entire Action Phase."
And this can be read in two ways.
Scenario 1)
Recoil penalties are cumulative over every Action Phase and Combat Turn unless the character spend an entire action phase on an action (or actions?) that does not involve shooting bullets.
Scenario 2)
Recoil penalties are cumulative over every Action Phase and Combat Turn unless the character take an action other than shooting bullets during a full complex action (=shooting bullets for an entire action phase).
In scenario 1)
If you have two IPs per combat turn then you can fire one bullet as slow as once every 1.5 seconds and still build recoil. To reset or to not build more recoil you would need to spend 3 seconds between your shots. With a revolver you could fire one bullet every 1.5 seconds and not build recoil.
If you have one IP per combat turn (which non-wired normal people have) then you could fire one bullet as slow as once every 3 seconds and still build recoil. To reset or to not build more recoil you would need to spend 6 seconds between your shots. With a revolver you could fire one bullet every 3 seconds and not build recoil.
In scenario 2)
If you have two IPs per combat turn then you reset or not build recoil you if you spend 1.5 seconds between shots (same for revolvers). To build recoil you would need to fire once every half second (you can not do that with a revolver).
If you have one IP per combat turn then you reset or not build recoil you if you spend 3 seconds between shots. To build recoil you would need to fire once every second.
Also... All Complex Actions descriptions (where shoot for an entire action phase) state:
p.167 Fire full-Auto Weapon
"Remember the effects of cumulative recoil when using these fire modes"
p.167 Fire Long Burst or Semi-Auto Burst
"Remember the effects of cumulative recoil when using these fire modes."
...while the Simple action description (where you don't shoot for an entire action phase and instead spend time to bring the gun back under control) on p.165 Fire Semi-Auto, Single-Shot, Burst Fire or Full-Auto does not mention anything about cumulative recoil.
Now... That might not automatically mean there is not cumulative recoil for the simple action where you also take another action instead of shooting the entire action phase and have time to bring the gun back under control, but it sure does indicate that there is a difference compared to the complex action where you do shoot for an entire action phase.