That is not training a customer, that is a trained customer. I know what a trained customer is, the question is how that training is done with difficult customers in regards to signing. I say you may have to walk out of the place of business with their packages, to get them motivated to sign quickly.
If the dock personnel never opened the door and set up the rollers before this driver bid the route I'd say he trained her to help him get in and out efficiently.
Hope the rest of the dock workers understand the daily process too in case she quits or moves to another dept.
Staying professional (and smiling if possible) and not letting slothful customers waste your time is a tough balance when trying to avoid an 800 call against you for being "rude".
Too many companies have streamlined their manning in receiving and a lot of dock workers have more work for the same $ now making their attitude testy sometimes. (No union at Walmart!)
We know that all too well ourselves. Just reference last peak.
But at least we have yearly raises.