2) It assumes that other countries will cut emissions as quickly as we do. But we know that is just not realistic because populations and living standards are set to increase in continents like Africa. Developed, wealthy nations like ours must cut emissions faster to compensate.

Answer

Regarding its 2050 net zero plan, the CCC states:

If replicated across the world, and coupled with ambitious near-term reductions in emissions, it would deliver a greater than 50% chance of limiting the temperature increase to 1.5°C.‘

Yet we know that even if less developed continents like Africa reduce emissions per person, expected population growth along with industrial development will cause overall emissions to rise, not fall. So in order for the world to cut emissions fast enough to stay within its carbon budget, more developed countries like ours will need to cut emissions faster than the average to compensate - like it or not.