I'm not trying to give you a hard time. I think you asked an honest, legitimate question borne of good faith. It's also clear, based on the images you posted, that these abnormalities are clear and obvious. But let's unpack the numbers a little.
Let's assume for a moment that this hypothetical radiologist read 100 cases per day (ha!), every day, every year, for the 5 years in question. Let's further assume that this radiologist works about 210 shifts per year. Just trying to keep the numbers realistic but also simple.
That means that a single radiologist working at that rate will read about 105,000 in a five-year period. What is considered an acceptable miss rate with those numbers? Because those two studies alone represent a 0.0019% of the total studies interpreted.
Clearly, this is not a comprehensive look at this one (hypothetical) radiologist's work, but let me ask a question. If you routinely referred your patients to a single surgeon for appendectomies, how many post-op abscesses would give you pause before referring to a different surgeon? Because at this complication rate, from your perspective, the surgeon is only getting 1 post-op abscess out of every 52,000 appendectomies.
So why do we treat radiology misses any different than any other medical complication?
I don't know the answer, but I do know that human beings--all humans--will reliably neglect to notice a retrospectively obvious abnormality a certain percentage of the time irrespective of other circumstances. I believe that conclusion comes from studying airplane spy photographs from WW2, but I admit that I have had a hard time confirming that.
My point? Start thinking about radiology misses in the same way that we think about all other medical errors. All of a sudden, we don't look so bad.