As to the first scenario, its hard to say whether the lab is to blame for the failure of the majority of embryos not making it to freeze. It could be that the lab is not as good as it should be in growing embryos out or it could be that the embryos would not have made it in any lab. What I find problematic is that not one of the three embies made the thaw. I think that is inexcusable and one reason why I would never consider a clinic that does not use vitrification where most clinics have thaw rates iof 94-98 percent. I have to assume that this particular clinic uses the old freeze method which is statically far behind in thaw rate than vitrification. That being said...that none survived the thaw is IMHO very telling.
As for the second scenario, I know of one very popular clinic that does not vitrify and for some reason, despite their high success rates on fresh transfers, freeze very little. They too have claimed that other clinics use less stringent requirements when it comes to freezing. I don't buy that. My clinic has requirements too as do most and will only freeze embies that are at least a grade 2 on a scale of 1-3 and have made it to expanded blast by day 6. IMHO, some clinics make this excuse because they do not vitrify and therefore will only freeze the VERY best embies as they have the best chance of surviving the thaw when frozen under the old method. If they had the up to date technology to vitrify, they could and would freeze more. We all know of MANY babies made from less than perfect embies.