https://www.relx.com/~/media/Files/R/RELX-Group/documents/pr...
Most journal reviewers and editors are academics who do the work as public service, i.e. free. Even top spots like editor in chief only get an honorarium of maybe 10k a year. Considering these people are the top of their field and can easily command 6-7 figures salary at minimum, that amount is nothing. Only very few journals have full time editors and even those end up relying on the volunteers to vet and review articles.
A full time professor is expected to be an editor for some journals. And these academics make up the bulk of "journal editors". But they would not list it as their jobs. I suspect that is why if you look for "editor jobs" you will get lobsided salary ranges that doesn't reflect reality.
You are confusing the parent company with the publishing part for that 19%, which is the main subject here. You are uninformed.
The www was quite literally designed for sharing scientific papers. Hosting them is a 1990s problem. The real cost is in building a paywall and enforcing it
https://www.glassdoor.ca/Salary/Elsevier-Editor-Salaries-E23...
I'm sure they have people employed called "editors" but they are not the same as academic editors who decide what gets sent to reviewers.
Ref? Elsevier (publisher of "Journal of Algebra") does pay their academic editors:
https://medium.com/@SiccodeKnecht/so-what-about-editor-compe...
For example, I'm on the editorial boards of three journals: Epidemiology, PLoS Computational Biology, and Infection Control & Hospital Epidemiology. I am compensated for none of them as an academic editor.
"Net profit margin: 19.04"
Look under the Scientific, Technical & Medical financial review. That is their scientific publishing arm.