(Question) How normal is it for ISPs Routers (CE,PE,PC) to have telnet, ssh, and FTP open to the internet?

(Question) How normal is it for ISPs Routers (CE,PE,PC) to have telnet, ssh, and FTP open to the internet?

Title pretty much says it all, but I'm currently studying ISP Networking (Nokia NRS 1) and wanted to know how common it is for that stuff to be open like that.

I have a fair bit of InfoSec knowledge to know that that kind of stuff shouldn't be open to the internet in an Enterprise environment, but I have no clue what level of normality it is in the ISP space. For example, looking on Shodan.IO shows a ton of ISP controlled Routers having SSH, Telnet, and FTP open to the internet.

Thanks for taking the time to read my question. :-)