Do shops still sabotage cars for profit?

My wife drives a 2003 Subaru Outback. Made in Indiana, probably more American than a Chebbie. Still, their dealer service network sucks. Overpriced parts, limited knowledge and/or training, and completely unwilling to share any service info. Ours developed an idle problem. Check engine light went on and codes indicated misfire. Local non-Subaru shop changed plugs and wires. Cleared codes, but the problem came back 1/2 block from the shop. Cleaned the throttle body and IAC motor myself. Seemed to help a little, but still codes and poor idle. Decided to try the nearest Subaru dealer. 100 miles away and only 1 to choose from. First thing they notice is the cat converter gets red hot. They want $2500 for the part. Also time to change the timing belt. $6000 estimate and they can't guarantee that the problem will be fixed. Of course, they are willing to trade me up to a new one. I decline. I buy a timing belt kit and a cat converter from the aftermarket. $650 total, but I still have not installed parts and I likely did not need them because I went back to the local shop. Took them another 6 weeks, but they found the EGR valve was stuck. Expensive part, Subaru was the best price on this one at $200, but it solved the problem. I'll change the belt anyways as it is time and the Subaru is famous for expensive repairs when that belt breaks. That cat converter diagnosis kills me! Subaru shop says it was plugged and that causes it to get red hot and idle poorly. BS! The cat gets red hot because it is working, burning up excess fuel which is being dumped out the exhaust because the idle mixture is too rich. Don't know why the EGR valve is not flagged in OBDII, but I guess that's the way it is. Subaru shop also told me the aftermarket cat was not compatible with the O2 sensors, i.e. no bungs. More BS. Still, the original cat is still on the car and works perfectly.

Another rant about parts pricing. Subaru is bad enough, but the local NAPA store will give you different pricing if you are off the street, (highest price), a member of an auto club like AAA, (medium price), or a representative of a large business, (lowest price). The spread from highest to lowest price is significant, say 50%. It's the same part off the same shelf in the same store by the same employee! All this special pricing must be extremely difficult and expensive to manage. Other than a blatant ripoff of the consumer, I don't understand why any business would not offer the best pricing possible under all circumstances?