Well, a smartphone is fairly bad for its small size, but we're talking less than 100kg of CO2[1][2] to make and operate for its lifetime. But driving a car for a year in the US produces 4600kg[3]...

1: https://www.cnet.com/news/apple-iphone-x-environmental-repor...

2: https://sustainability.google/reports

3: https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t...

You are right. Few do. If people cared about the environment that much, they would have lobbied for laws against planned obsolescence. Me buying 5 phones or even 500 won't make a difference to the environment. Laws forcing phone makers to support their phones for a minimum of x years might. Clearly, our society is not interested in that. Why should I then go out of my way to inconvenience myself to do something that will make zero difference? No reason to at all.

Typically price is a pretty good indicator of the amount of resources that went into making something. I'd expect the environmental cost of an iphone to be a similar multiple of the environmental cost of an android.