Nope, not a newer thing to use purple for the funeral industry.
1. See the above 1930s-1940s light in purple FUNERAL.
2. The funeral flags/banners used for many years in funeral procession, yep, purple.
3. In 1956 when the Fire Ball came out, for a short time purple/magenta domes were offered in a funeral supply magazine. (I wish I could find one.)
4. For many years, purple has been considered a color of mourning.
Although not universal, purple lights have traditionally been used for the funeral industry in the USA and Canada.
Before the 1940s the only color readily available for emergency lights was red. Once other colors became easier to manufacture, they took on particular generally accepted meanings. One of those generally accepted meanings, purple/funeral.