I am pragmatic, not following the OSI definition of open source, as the general public does not seem to do so either.
As a software developer, FOSS contributor and user, I am well aware of all the differences. When I think about open source, its mainly that the source is open - because that is what everyone can and will understand of this term. Even if a program is only sold or a rented service, if the source code is available (even if unusable besides personally studying it), it is open source.
Free software (as in freedom) on the other hand gives you freedoms of use. So when I want to name or look for these, I look for free software. Not for open source software (which free software always is).
As the term “free” is always ambiguous does not really help, but at least if you look or name FOSS, or “free as in freedom”, you know what you have. If you look for open source, you’ll have to check the license anyway, because naming software with available source “open source” seems to be common.
How else would you name those anyway, if not open source? The source is available, so the OSI definition does not really fit the general term “open source”, because how would we name that stuff then.
When someone else names something open source, you never know what he is referring to. You’ll have to check the license anyway. It’s all really confusing, especially to outsiders and less knowledgeable people, who may not even know or look for licenses on software.