I have no idea, I have joined a US based Facebook group where I monitor things happening, and there seems to be pretty much the same. I have mostly done mystery shopping in things like suitcase stores, eyeglass stores, car dealerships (with test driving). My favorites are restaurants and situations were the shopping company has a strict deadline and someone just cancelled last minute during the holidays... :-)
I've done grocery only once were the main goal was to check wether or not they asked for ID when buying alcohol under the age of 25 (inustry norm), but I don't think it's so common.