100% anonymous VPN/Proxies (to what extend is that TRUE?) - Seems impossible?

When VPN and proxies providers claim that they do not keep logs (100% anonymous). To what extend, is that true? I am curious because even if they (themselves) dont keep logs, the ISP or IP provider/owner (whatever you call them) do a record of all activites as well.


I dont have a full understanding of how it really works, but I am guessing it works like this:


ISP > VPN provider > clients


So even if VPN providers erase/delete all logs, the ISP (highest tier) will still have all logs stored to some extend?