The information asymmetry I was referencing was simply the knowledge of whether data is or is not recorded and how much is recorded. A VPN service that records more data is what I would consider a lower quality product and a lemon. Once a company starts collecting information it can use that data for a variety of other purposes such as selling it to advertisers. That extra revenue stream is what would make a lower quality VPN product cheaper than a higher quality one with no logging.
Also the end result of a market full of lemons is something that develops over time. I don't think the VPN market is mature enough for buyers to have learned to presume a lower quality product. I would even argue that the information asymmetry is so extreme in the case of VPN services, that a user can purchase a product, user it for years, and still not be able to accurately assess its quality. This would slow down the development of a true market for lemons.
The "Market for Lemons" dynamic has an earlier precursor, the horse trader. In looking up Gresham's Law references, I've run across H.L. Mencken's "Bayard vs. Lionheart" (1926), which references "David Harum". That was a novel, and film, and later (after Mencken's writing) a radio serial, about a horse trader.
Horses, as complex and nonuniform goods, had developed a reputation for unreliable and underhanded dealing. The lasting legacy of the novel itself is the expression "horse trading".
Also the end result of a market full of lemons is something that develops over time. I don't think the VPN market is mature enough for buyers to have learned to presume a lower quality product. I would even argue that the information asymmetry is so extreme in the case of VPN services, that a user can purchase a product, user it for years, and still not be able to accurately assess its quality. This would slow down the development of a true market for lemons.