Yes, it is store policy. I worked for a Husqvarna dealer for 3 years inside a JoAnn's and they do have to show their purses. They also have to look in any bag you have. They couldn't 'require' me or my staff to show our purses but we did so voluntarily.
Those folks have it harder than many of you realize.
And, yesterday all the ladies at the cutting counter were pleasant and interested. A lady working in patterns escorted me to where they moved the felt (she said, "I'll take you there, it's really hard to find".)
They have to work all night Sunday night when the 'reset' the store. They have 'mandatory meetings' at 7 a.m. in the morning (some of the guys came in their sleep pants, snow boots and heavy jackets.)
They had posters in the break room of a big thumb with the captions "thumb mistakes are costly". They're not supposed to give even an extra thumb's width of fabric.
Yes, sometimes they are crabby or not helpful but all things considered most of the time they do a pretty decent job!