It is - and I’ll elaborateTaxes collected can be direct and indirect. In case of most developing countries, the per capita income is so low that the direct tax collection is equal or lesser than indirect taxes. In India for example, GST collection is 60% of total tax collected by the exchequer. Given that indirect taxes are placed on ALL citizens of a country equally -- can people still claim that only the 'middle class' is paying taxes? This is an insult to the lesser fortunate people.
The indirect aspect which you speak of in terms of Pakistan is a direct result of the inability of the Federal Revenue folks to collect paycheck/earnings/profit taxes directly from the majority of earners in Pakistan except the salaried(and by that formally salaried class through organizations). We have NO or negligible earnings coming in from larger corporations especially those not recognized MNCs but running immense empires based on real estate or agriculture in Pakistan.
There is no direct taxation as such of a massive cash salaried class of which the less fortunate are a part of but also massive loss due to tax evasion by businesses and land owners.
What that leaves is the directly taxed middle class who incidentally also pay the indirect taxes along with everyone else and have the added burden of(by socioeconomic and religious factors) supporting the impoverished class as well through alms and general support.
This middle class is still expected to create new businesses, keep existing ones running along with the entire functioning of the state as well.
This also bleeds into creating motivation for corruption, regardless of the inclination towards it - today it is next to impossible to keep a couple in the middle class category.. forget children . Just a married couple cannot afford rent on a single bedroom place with a 800cc death trap car along with expenses on a typically expected middle class salary for Pakistan.
So this class is being pushed into poverty or forced to migrate. They can forget about EVER owning a property unless they inherit it and even the most basic of vehicles on a lease(nearly impossible to get approved for now on that middle class salary) is near unaffordable.
So while your taxation example is great for Canada or the US where the middle class still has a livable standard (even though that is under attack too) they can maintain fairly well - it complements fails the litmus tests for fair and proportionate implementation in Pakistan