I don't know how you read parents comment and concluded that they're talking about some conspiracy. They seem to genuinely ask a question that I'm sure they're not the only one thinking about.
> In 80's people use more glass containers because they didn't have choices, not because they love to carry heavy glass containers around to help the environment.
Again, don't think they said that people used glass containers back then to help the environment, just that for whatever reason they used those containers, it was less harmful to the environment. Not because that was the reason, that was just a side-effect of glass being the only choice. Then they ask the community what the reasons could be for everything being wrapped in plastic now.
As it reads right now, your comment doesn't seem to assume good faith of parent comment, but instead you're arguing against some position that isn't even talked about.