I don't know what you're talking about. I get order confirmations from retail stores all the time with full details of my order, every item listed in full detail, last 4 digits of credit card used, etc.

I see no change in this over time, nor do I know why companies would even care that an e-mail provider (including Google) would be able to read that information. I don't think this phenomenon exists at all.

The only thing I can imagine you referring to is companies having the tracking link open to their own page rather than directly to UPS/FedEx etc., but that's for totally separate reasons that you can see from Narvar's marketing.