Zygosity: why does it have to be so hard?

When we first found out our twins were, indeed, identical, I believed that the intial mistake in their zygosity was just a fluke. Their placentas were, after all, on opposite sides of the uterus. According to my OB, it was so highly unlikely that they were identical that he hadn't even considered it.
From what I understood, cases like ours were rare.
Not so.
Over and over again, I hear of twin parents who are told that their twins are fraternal, but who still simply cannot tell their twins apart. They post photos of their twins on online bulletin boards, hoping for answers.
Like us, those parents are told that the placentas were tested at the hospital. The babies can't be identical: just look at the results, the doctors say. The parents scratch their heads and try to persuade themselves that the hospital and the doctor must be right.
What doctors don't say is exactly what kind of test the hospital has conducted.
Here's what they do: Hospital simply conduct a physical test of the placentas. The lab tech studies the membranes to determine whether they were two fused placentas or one shared placenta.
That's it.
DNA has nothing to do with it.
In our case, that was a no-brainer.
Matthew and Jonathan each had clearly distinct placentas and, so, the results on my OBs computer said "fraternal." He assured us that many twins look identical when they are born and that they would differentiate as they got older.
That never happened.
If anything, they look more alike.
We finally had our boys tested when they were infants. It was easy. We received a kit in the mail for about $170 and rubbed large swabs gently inside their cheeks. We put the swabs in the test tubes the lab provided and mailed them off in the box the company gave us.
The results were supposed to take three weeks.
We learned the boys were identical a week later.
Every single one of those parents I have met online later learned through DNA testing that their instincts were correct: their twins (and sometimes two of their triplets) were indeed identical despite the protests of their OBs.
I'm not sure why some OBs still subscribe to the old theory that two placentas equals fraternal twins. Their information is outdated and so much evidence exists to prove that their methods are faulty. Just take a look at this 1999 study. The author urges OBs to change their evaluations if for no other reason, because the twins simply have a right to know.
So why does it have to be so hard?