Thank you for commenting before me. I was thinking the same “If Delhi’s air is so populated with BS6 engines and BS6 fuel, can Lahore gain much air quality improvement by switching to Euro5 engines and Euro5 fuel?”
The comparison clearly means that the culprit is something else. In fact in Lahore too, the cross-border smoke from crop-burning is the major polluter, but due to “political diplomacy” it is never shown in the media except for when the Foreign Ministry wants it to use it to their own advantage. The farmers of West Punjab and the local brick-kilns also have the same lawless behaviours, but the volume of economic activity is lower than East Punjab and so the contribution to the pollution is also lower.

There has been an article in this vein: https://carspiritpk.com/switching-euro-5-solve-environmental-problems/

Although I do not think that Euro6 or Euro7 is wholly draconian. It is very important to shift to low-polluting fuel so that older vehicles, and non-engine uses of fuel also see the environmental benefits. In Pakistan all the (new) cars shifted to Euro2 in 2012 but the oil refineries took till 2017 to begin producing Euro2 compliant fuel https://carspiritpk.com/euro-2-in-pakistan-a-decade/#comment-9498. I agree with your take that lower-income countries like Pakistan and India should not focus on individual vehicle-owner for pollution-reducing measures, but my stance is that it must gain cooperation from fuel companies to produce low-polluting fuels https://carspiritpk.com/blame-where-the-blame-is-due/#comment-7829, https://carspiritpk.com/8-years-of-euro-2-in-pakistan/#comment-13646 as well as lowering absolute fuel consumption (emissions control systems actually increase absolute fuel consumption by quote an amount).

Aam Aadmi Party rules both Delhi and Punjab and used to shout about these things when they were in opposition but now they rule Punjab and can’t risk losing those rich farmer votes which accompanies with muscle power/street power.