Some SAPs should be easier to ninja, like passive.
If you can field an army of Vagabonds, then that's great, the attcker will need to clear them out before they can make any progress on the hack.
There's a sort of hierarchy and balance to the SAP difficulty, you may lose every passive SAP, because tossing a tank on there is really a good offensive strat that takes a significant effort to counter; Small offense, big defense.
For active hack, coming with a single tank and a hack module isnt such a great strat, even with eccm, your going to lose lock every few minutes for sure, and you'll never complete it. A small defending force can counter a small offense. Tanking defense on the active hack would work too, meaning defense can put an ECM tank out there and counter a fairly large offense.
Speciman saps need a lot of effort from offense, so your likely to need a larger defense to counter it. A single ewar isn't going to ninja a speciman sap.
Destruction, with the change, is one of those that could go either way. A single bot could destroy a totally undefended SAP, but the more defense you put on it, the more offense they'll need.
Difficulty of the SAP shouldn't be the same, and it doesnt seem like it is.
All of them should need active defense, and they've definetly done that.