In civilized countries...
"It doesn't really make economic sense to have a fax machine physically they days just based on the line rental costs."
In civilized countries, companies have a trunk telephone line anyhow, so a fax machine only uses one port of your PBX which you usually buy on boards containing 8 of them.
Using external FAX-providers is not only bad security wise (an additional company handling your data creates additional possibilities for malevolent actors), but also a huge problem with reliability. You have more components in the way, each one could fail, and once you leave the fax protocol domain, failure will not be reported to the sender. If you have a full "fax-to-fax" connection, your sending fax will only say it's OK when the receiving fax acknowledged its reception. For some faxes that even means that the fax was printed out already.