This is a customer card that used to accompany Shenzhouxing prepaid SIMs, which, based on my recollection, were strictly pay as you go (i.e. draw down against balance for voice/SMS/data at established tariffs). The advantage of that style for occasional visitors was/is that you can keep your number for a long time without paying any sort of recurring fee.

I think these SIMs might still exist in some places (tiny villages, perhaps?), but I haven't seen or heard of any since real ID became a real thing... around the same time that street vendors and airport kiosks stopped selling them.