The problem with that claim is that, yes, they all conform in one way, and to one degree or other, with these standards. But they don't all conform the same way and there are just enough differences, nuances if you will, that cause content to be non-inter-operable.
What does that mean for you, the customer or end-user of these learning management systems?
It means that the content you buy with the assurance it will work on "any" LMS is more of a wish than a reality. Not that the content or LMS vendors are lying. They'renot exactly. Most live in their insular development environments reading exciting SCORM and AiCC standards docs. In their minds, they are conforming to the standard... Problem here is that the standard allows some leeway for vendors to delineate the content of certain variables.
For example, here is a variable: lesson.status and some possible results:
Some vendors even have different responses to the same variable across the two major standards (SCORM and AICC).
The bottom-line is that it will cost you big time to port your content from one LMS to another if you decide to change LMS vendors. It will also cost you when your content provider may need to make changes in order to have their course work in your particular LMS. Or when you pay my company to fix the same problem for you (we do a lot of this).
I think it's time "inter-repeatability" meant what it implies. All content should be able to run on all LMS without ANY modifications to the code and re-publishing. When that happens, we will truly have inter-separability and you, the end-user or customer, will have made a good purchasing decision...
Solution? Ensuring that the standards are tightened up and made consistent and that LMS vendors not just put a logo saying they are SCORM or AICC compliant but actually "certified". Till then it will be buyer beware and be ready.