the specific argument you put forward is rather weak

I wasn't claiming to pick the most environmentally destructive thing that people do. I was just picking a random, easy-to-understand thing that seems innocuous but still contributes to climate change. People know that driving cars is bad for the environment, but often don't stop to consider that eating a banana could also be bad because of the shipping.

the problem cannot be solved from the consumer’s position

Not completely, but consumers can change their habits and make a significant dent in the problem. For example, "people sitting in tons of steel making short trips". If people stopped driving, or at least significantly reduced it, that would have a real effect.

I'd argue that the problem can't currently be solved by voting either. Yes, government regulation eventually has to be the answer, but right now there are too many people who would vote against that kind of a change, or who at least wouldn't make it a priority. And, with all the fossil-fuel special interest money flowing into politics, even if it is a priority for a voter, there will often be elections where both major party candidates are in the pocket of the oil industry.

If people change their own personal habits (i.e. stop driving) that makes a small dent in the problem. But, it also motivates them to try to campaign, run for office and vote for other people who will make that kind of a change. If you stop driving you realize how much cities are geared around driving. How many hidden subsidies drivers get, etc. If you keep driving but just vote for candidates who talk a good game about carbon taxes, when they back down on those promises you sigh but you aren't highly motivated to keep pushing.

Let me just buy some locally grown bananas, in the north…

That's my point. You can't. If you want to not be responsible for those CO2 emissions you have to eat something else.

It is totally up to the governments to regulate emissions, with regulations.

Sure, but you also have personal agency. You can choose to eat beets instead of bananas. You can choose to pay to have an old monitor fixed by a local repair shop instead of buying a new one. Instead, people use the lack of government rules as an excuse to continue to live the way they want to live. They choose to blame corporations for polluting instead of their own choices as consumers.

If I want a banana, I’ll get a banana. I will have no idea or information whether it’s shipped with the shittiest fuel burning ship, or an electric locomotive.

Yes, because you don't want to know. You will never do that research. Admittedly, the research is hard to do. It's hard to do a complete calculation of all the CO2 costs of the entire chain of events that results in a banana on sale at a local supermarket vs. a locally grown beet.

People could choose to try to do that research, but they don't. It's hard, and it's depressing. Instead they'll feel good about recycling an aluminum can, and never think about the environmental impact of driving around the city in a car.

And will people vote for stricter emissions laws and/or carbon taxes? Some people will, many people will vote against it. Many of the supporters will also not make it a priority. And, if the party that promised carbon taxes and/or stricter emissions wins but then gets lobbied and doesn't enact those new laws, very few people are going to go out and protest.

The government's lack of action and the idea that corporations are really to blame for CO2 emissions is a convenient way for people to continue to live their massive energy footprint lives, while shifting the blame to someone else.

The key is to do both because they are principally coupled and nothing happens as long as consumers and corporations just point at each other and use it as an excuse to keep on going like before.

Of course you are right that the focus should lie at changing CO2 output at the producer side because the influence is much more focused there. N my opinion it is also dangerous arguing that the companies only supply what the consumers want because that statement is based on the consumption and is biased too much by what the companies offer and at which price. Consumers usually socioeconomically do not have the choice to buy a product at 1.5 times the price, even if they would prefer it for environmental reasons while these companies have immense profits and can and must afford to reduce and finally stop emissions.

And, how likely do you think that any laws are going to actually get passed?

People's consumption is the only real thing they have agency over. They can vote, but if voting is more a placebo than an actual way to change things.