Your friends daughter was hopeful and excited and then suffered a loss that’s tough and difficult and your friend said the wrong thing in that moment. Regardless of that being ‘true’ in your day, that moment was really should be about your friend offering comfort and reassurance to her daughter in a difficult moment.
All the debate about ‘early’ testing is moot, the comment was hurtful in the moment, albeit unintentionally.
My understanding was that the tests detect HCG and the body doesn’t start producing this until implantation begins. The sensitive ‘early’ tests just pick up on smaller amounts of HCG. So we know a little earlier, yes. But there was an embryo- and knowing that means there was a loss suffered. As noted by others this is important to know when considering what fertility issues might be present.
The ‘just relax and have fun’ is also a challenging rhetoric that doesn’t fly when you have fertility issues, those same fertility issues means you do need to track fertile windows and test early. Because your body might not be predictable in that way.
As someone who has gone through fertility issues, I sympathise with your friend’s daughter. Her mum needed to offer support in that moment, not social commentary.
I am also assuming that ‘back in your day’ there wasn’t the internet to talk and rant about such things in an anonymous forum, but regardless we are where we are.
The modern day has ‘early testing’ and the consequences of that are people are informed earlier about what is happening and important information about whether they are fertilising embryos that later fail. It has pros and cons but we are where we are.
Your friend should apologies for being tone deaf and insensitive in that moment.