In the '80s, the industry was at the centre of an environmental backlash. Fearing an outright ban on plastics, manufacturers looked for ways to get ahead of the problem. They looked at recycling as a way to improve the image of their product and started labeling plastics with the now ubiquitous chasing-arrows symbol with a number inside.
https://www.cbc.ca/documentaries/the-passionate-eye/recycling-was-a-lie-a-big-lie-to-sell-more-plastic-industry-experts-say-1.5735618

...preto vsade kackujem dobsa ked trpezlivo vysvetluje ze bez rozmyslu ziadat nekonkretne ekologicke opatrenia (ako napr znizovanie produkcie co2, zakazovanie veci bez jasnej nahrady) nemoze skoncit dobre