At that time, how did text programs, spreadsheets, and other tabular reporting applications output in Landscape to contemporary dot matrix printers?
For businesses that needed wide printouts, it was common to buy a wide carriage (tabulator type) printer. For example, Epson not only sold the MX-80, but also the MX-100 with a wider carriage able to handle up to 15 inch paper, allowing up to 256 characters per line (using a condensed font).
Using condensed font was as well up to 132 characters on standard paper, which should be fine for most applications... After all, 132 was also the default format for wide prints :)
While this was fine for most users, after all, a table with more than 132 characters is already hard to handle on screen, there was no way around with early software using ASCII output.
For a printer to turn this on its own into landscape, it would need to store the whole output for a page first and then turn it into a bitmap. This would require a buffer at least large enough to store like 4+ KiB of text plus whatever control characters are needed (all just for ASCII, no graphic borders). So more likely 8 KiB. In addition at least some bitmap line buffer must be present. Consider that the MX-100 had just 256 bytes total buffer. And that was a printer with a price tag close to 800 USD in 1981.
There was also no simple way to do it on the host system, as drivers that could do the job were not part of the OS (at the time) but part of each application.
Nonetheless, some applications did support a few (mainstream) printers during the mid 1980s. But it was a case-by-case issue finding the right combination of program (and fitting computer) and printer. So the average user didn't - and professional users with a certain need simply spent money on wide carriage printers.
For major packages like Visicalc or Lotus, application-specific extensions were offered. Examples for somewhat generic solutions are the "sideway option" for Borland Sidekick, or the Printer-Boss package from Connecticut Software. They hooked the BIOS printer calls, emulating a certain printer (usually Epson MX-80). Data was collected until einter a 'page' was filled or the buffer overflowed, and then printed. The buffer overflow condition happened usually quite fast, so anything wider than 2-3 pages was at risk of failing.
It was again an advantage for Apple that the driver structure for MacOS was better placed. Already with the Lisa it was possible to print in either orientation, as printers were only operated as bitmap anyway.
Windows and GEM offered, a bit later, the same service for PCs.
It's also useful to keep in mind that early (and somewhat affordable) laser printers also didn't have the memory to hold a full page of bitmap. There several third-party companies built add-ons to allow full page graphics.