I already keep finding texts with no space after a full stop. It often happens in newspaper articles,

Because newsapers and magazines generally use narrow columns, it is very common to "compress" each line so that the edges, especially on the right, aren't "ragged."

This is usually done by narrowing all of the spaces in each line, or in some cases by stretching them all. Unless you've got a very good eye and understand how it's being done, shortening a double-space may look like only a single space was used. Few people can tell the difference consistently when looking at printed work.

A similar "adjustment" is used in book publishing, where it's considered important to prevent "rivers" where spaces in each of several lines (usually three or more) all "line up" with each other so that it looks like someone slashed the page with a knife and made a gap that runs down the page.

Similar effects are applied to line spacing (leading) by professional publishers, so that the number of lines on a page may vary (by one or two lines either way) without being visually obvious to the reader. The leading adjustment is used to avoid "orphans" where most of a paragraph is on one page with an "orphan fragment" (only one or two lines) on the preceding or following page.

A difference between Word Processing programs and Page Layout programs is in how easily, and to what exxtent, effects of these kinds can be applied. A very skilled user in Microsoft Word (until version 2007 when they hid - or removed - all the tools) could use, or at least closely emulate, most of these. Page layout programs like PageMaker (mainly used by book publishers) and FrameMaker (best suited for magazines and newsletters) make it easier, and usually allow finer adjustments.

The program doesn't matter much if the "typespiller" doesn't know what should be done. And for nonprofessional work it doesn't matter to most readers (if there are any).

John