Why do you think BP produces emissions? They may be evil, but it’s not out of malice, it’s for profit. People, like the 26 million residents of Australia, pay BP to give them more fossil fuels.
A top-down response, where governments just outlaw all extraction and burning of fossil fuels, would be a lovely, quick solution to the climate crisis. By all means, try and make that happen, but I wouldn’t hold my breath.
One thing you can do today to make an impact is to adjust your lifestyle to give less money to the fossil fuel industry. An individual carbon footprint is small compared with a company, just like the money they give to BP is relatively small, when compared with their total profits. But when you add up all the customers, their money adds up to the revenue of the industry, and their carbon footprints add up to the footprints of the relevant companies.
You’re arguing that the actions of individuals have no impact on the collective actions of humanity, the sum of 8 billion individuals.
Similarly, you probably never had a conversation where someone said “Gee, I’ll stop burning fossil fuels now!” But when you use public transportation, or patronize businesses on foot, policy makers are motivated to continue supporting such options. Not for you personally, but for you and others like you.