The Chinese invented paper about 8 AD. Tissue paper is just a thin form of that, and dress patterns are typically printed on tissue paper because it's cheap and light and cuts down on expenses. Some companies print their sewing patterns on newsprint (MacPhee), some on high quality, opaque paper (Kwik Sew). Many companies, especially the "big 4" (McCalls/Butterick/Vogue/Simplicity) use tissue paper. Patterns used for ready to wear production are printed on a heavy paper also, sized to fit the fabric — this is called a marker.

Here's someone using an industrial cutter and a marker to cut a stack of fabric:

Unfortunately, tissue paper patterns are probably the least accurate method of receiving a pattern. Markers are the easiest and most accurate.

(BTW, do a google search for the words Butterick and Deltor together)