The requirement for a smart phone actually started a few months ago. I did the first one requiring a smart phone in September 2019. It's really easy - you down load the App. When checking out, the cashier is supposed to ask if you are a Loyalty customer. Whether they ask or not, you are supposed to log in on the App and show them the number to get loyalty points. Very easy and you earn points for future visits. Warning - on the receipt it will print "Loyalty customer" with your name. Be sure to cover or scratch that out, the MSC doesn't want your name visible.
Several other companies have gone to Apps. Ardent's burger chain has been using apps on their shops for several months and I love it - it cuts down on the number of interactions, I don't have to stand in the cashier line, and it makes an easier report. A lot of fast foods and fast casuals now use apps. It's probably only a matter of time before they start to require that those apps be used by mystery shoppers at least part of the time.
TrendSource has an app that lets the mystery shopper clock in when he enters a client location and clock out when he leaves - simplifies the report. I like it. I started using Geoverify just recently and discovered I didn't mind it as much as I thought I would.