Many science journals have small circulations, and it is an issue to get the articles typeset and archived. Small literary journals usually do not include glossy paper, color, printing 1000 pages an issue, or full color figures, so far as I know.

The economics of paying the page charges are not an impediment to writing the papers, finding results interesting enough to write up is the hardest part. Scientists laboring to write coherently can be a challenge, as well.