That would pretty much be where the hate comes from...It is common for tanks that Pass their Hydro testing to Fail their VIP,...
where does tis hate for LDS's come from?
You are absolutely correct that the hydro and VIP test different things.
At the risk of repeating myself excessively, a VIP is a required part of what is commonly known as a hydro test. Both the hydro test and the VIP make up what is legally known as the requalification process that a tank has to pass before it can be restamped with a new requalfication date.
So...a VIP and hydro test are both legally mandated parts of the requalification process. The tank does not get stamped without passing both. It is also worth noting that the dive shop's VIP does not count here as far as the DOT is concerned, it has to be done by the test facility.
The dive shop does its own VIP for reasons of its own, but if they fail a tank that just came back from hydro test, they probably screwed up or shoudl be contacting the DOT to have them inspect the tank and the test facility that requalified it. If a shop commonly fails the VIP on a just hydro tested tank, I'd seriously suspect either their competence or their honesty and it would be those few incompetent or dishonest shops that generate a disproportionate amount of the hate toward dive shops.