Now, I'm not a tailor, but...

I recently came into possession of a new pair of pants.
They're a nice pair of pants, all things considered. But one thing really, truly annoys me.
The buttons...

Buttons seem to be a real problem with the manufacturers of pants lately, because, well, I run across this problem alot.
You see, the button, affixed to the pants above the zipper has come loose. Such that I know it will eventually pop right off. Which is compoundedly annoying for this reason - the manufacturers of these pants have sewn two (2) extra buttons to a tag on the inside of the pants.
Which means that they knew that the button would pop off if worn for anything more than 5 times.
But as I said, this whole button thing is a problem I've had with other pants... Which means that I have gained the experience necessary with a needle and thread to actually sew a button back onto a pair of pants.
What I don't get is this...
Every button that I've sewn onto a pair of pants has never come off. Even if I've worn the pants more than 5 or 6 times, my sewing has not come loose. I'll even stretch that to say that I've worn some pants 30 or 40 times and the button has still not come loose.
AND yet, the manufacturers of pants, who are trained (hopefully) workers with some skill in designing fashionable pantalons can't sew on a button so that it will remain affixed to a pair of trousers for more than 5 wearings.
But the two buttons they sewed to the inside of the pants are still there...