How is the Recommendation Rate connected to the Decline Rate?

When researching specific declined jobs, several patterns emerge:

1. If jobs are recommended too often (every  or every other RO), the Decline Rate goes through the roof and is above 80%, questioning whether that process is 
   1. Discouring the Service Advisor (SA), ultimately giving up on trying
   2. not considering the proper need
2. If jobs have decline rates of less than 10%, is it due to 
   1. Low recommendation rates, estimating with the SA's "wallet"?
   2. There is no consistent process. The DVI process is left to the staff, and techs only recommend jobs they know the SA can sell.
3. Engine and Cabin Air Filter jobs are the most declined jobs, by far. Why? Shouldn't the DVI help educate motorists better than any time before?

Let's take two shops, A and B with the engine air filter numbers as shown in the screenshot below

You could frown upon shop A's high decline rate and praise shop B's low decline rate. 

The actual pattern is that Shop B under-recommend the engine air filter replacement. The low recommendation rate suggests that only slightly more than 10% of all customers receive the recommendation. 

Shop A has a healthy recommendation rate of 25% of the customers receiving a recommendation to replace the engine air filter. 

It turns out that the job opportunity, taking the approved and declined jobs together, shows that Shop A has a bigger opportunity to implement a better process since consistency is in place. All it takes is to help the SA educate the motorists for a higher approval rate.