I always hear this, this is a 'small part' that is a 'small part'.... well guess what, many small changes add up to something big. People can blame big businesses but ultimately it is consumer demand that causes it.
Small changes only add up to something big if (a) there are enough small changes and (b)
they are changes in the right things. In this case, neither is true.
If someone has a broken leg with a gaping wound in it and also has some much more minor cuts on their arm, treating the cuts on their arm is of some use and should be done but it won't "add up to something big" in terms of helping with their injuries.
In the case of emissions, "add up to something big" would require massively restricting international trade and travel. Which would be hugely unpopular, massively harmful to many people and probably impossible anyway.
The ordinary people can only stop using their cars but that will ultimately mean another economic disaster, and many businesses go bankrupt.
Isn't it simply easier for the automotive manufacturers to stop immediately making ICE vehicles?? [..]
Easier, maybe. Although of course that would also "mean another economic disaster, and many businesses go bankrupt". Businesses involved in cars, of course, as all of the knowledge and most of the parts become irrelevant, but also pretty much everything else since the effects would be the same as "ordinary people stop using their cars" since the infrastructure to support universal EV use doesn't exist, can't yet exist and wouldn't be sustainable if it did exist. So people would indeed stop using their cars because they wouldn't be able to use their cars.
High concentrations of CO2 are used in greenhouses to speed up the growth of plants but the greens and climate emergency alarmists want zero emissions, if plants were to become sentient the equivalent would be like them getting together and agreeing to zero emissions on oxygen. Photosynthesis forms the cycle of life on Earth.
Do we need to cut down on other pollution? yes, do we need to reduce deforestation? yes. but the "climate emergency" scare due to CO2 is laughable, plants will be loving and thriving on any increase in CO2 and they will produce more oxygen as a result.
Even if that's true (and don't think it is because I think that the CO2 output exceeds the ability of existing plant growth to process it), that would be a different problem. The very large amount of oxygen produced as a result would increase oxygen levels in the atmosphere and that would be a problem. Humans can breathe air with much higher amounts of oxygen, but it would significantly change the environment in a variety of ways. Most directly relevantly to us is that it would increase the risk and severity of fires.