That's been my experience too. We had purchased some vernier calipers from a very, very well known manufacturer and didn't ask for a full certificate. On sending the calipers to a cal. lab. it was found that they were off quite a lot. It was the manufacturers way of 'grading' them, if you asked for a full cert. at time of purchase. The people who didn't ask for a cert. got the 'off spec ones' I'm sure.........
So, although it might seem more costly, the reality is this. You must know the condition of the items, so that you can make an infomred decision, based on data, about the suitability of the equipment for the task, then set a recalibration recall. If the equipment is 'close to the edge' (YES, circa 1972), then you might not get to the end of a year without a problem - of course it might have cost more than the certificate.
My advice - get the full cert from the get go. Your tech was correct! And by the way, ISO says you have to base your decisions on data (8 QM Principles) not cost........
