I don't think people are stupid but I think they have a limited number of sources from which to derive their information. And history and science are not discussed by everybody.
If you live among university-educated people, then, probably, at some social meeting, a woman complaining about some unfairness at work, in the canteen or gym or something, that is directed at women users, say the women's as opposed to the men's cloakrooms, will be met with the clichéd, jokey comment: ' So you're going to chain yourself to the railings/canteen counter, on Monday morning?!'. That way, references to history slip frequently into conversation/consciousness - even though few will have taken the trouble to read up more on the Suffragettes.
Actually, the Suffragettes are often referenced when Year 11s are studying the GCSE English Language play: ' An Inspector Calls', set in 1912. I could say parents should know this and have mentioned it, if they bothered to take an interest in their kids' homework. It's a bit elitist to call people stupid. Two things are certain, people have different outlets from which to get their information and news. It's not stupid not to know something which you haven't been told about.
Yes, we do trust big organisations, such as government and trading standards to keep our products safe for use. We don't investigate each single one, ourselves. I just read about Zoflora, and invented in 1922, it enjoyed an enormous surge in sales in 2018, when Mrs Hinch recommended its use. Actually, I would say that it is odd that Mrs Hinch and her team don't research products and find out about nasties and scares, which might make it not a good idea to endorse something. But maybe that is because there is a matter of opinion and relative degrees about it. Maybe many people think that products would not be on sale and passed fit for use, if dangerous. That would be a reasonable assumption. After all, we are told to trust, what do they call it, 'peer-reviewed scientific evidence' about vaccination etc, so why not trust trading standards when it comes to cleaning products?
But, then again, perhaps rather than saying people are stupid, it would be truer to recognize that we all get more information from social media platforms, these days, and maybe advice is not so thoroughly researched as it used to be when we gained information from columns in daily newspapers, or those programmes which come on TV after the six o'clock news. Maybe that is why harmful garden products get recommended on social media, whereas housekeeping articles in the magazines we all used to buy would probably have been more painstakingly researched. So blame the internet and it's lack of scrutiny and policing, rather than people being stupid.
Anyway, experts are always changing their minds about whether washing at low temperatures is enough to kill bed bugs/germs, or not. Some people trust that a cleaning product wouldn't have been passed by the government agencies as fit for sale, if very harmful to the sit we and our pets breathe. Some people may even want to be safe and think that the flowery smell of Zoflora means that it isn't bleachy or abrasive, as it doesn't smell in the same way.
If you are going to wash and reuse plastic drinking straws, then you are doing your best to save the planet. Perhaps some people genuinely can't get on with the paper ones. I think the problem has been fast food outlets always selling drinks with a straw which then gets binned with the carton: why can't people drink straight from the cup? Save paper in the paper straws too? But the disposable culture is part of the times we live in, and both partners working rather than sixty years ago when women tended to stay at home preparing meals and packed snacks, and takeaways were a rare treat, rather than an essential way to save time because work takes up so much of it, and kids need to be collected and office targets met. People are allowed choice. Some people drive and run a car and yet congratulate themselves on being ecologically-friendly. In London, we have good public transport. You probably don't need a car.
Maybe Grade 5 at GCSE sounds low, to some people, but don't forget many young people can't study peacefully at home, have to care for younger siblings, or move from house to house and different relatives to fit in with family plans. Some even work on Saturday and Sunday to help out the family budget. So, it's mean and not very considered to suggest that people are stupid.