The cost of automating car construction is quite costly. The cost of automating website construction is near zero. That is the number 1 reason why you can't compare these apples and oranges.
One of the top reasons why blue collared labor is being phased out is not only due to outsourcing, but also from the installation of robotic workers (i.e. Amazon's warehouse infrastructure). One of the fundamentals of programming or software engineering is the ability to reuse code, modules, frameworks, you name it. With this level of automation already in place and still growing, there's absolutely zero need for this class of blue collared knowledge workers as you've described.
One of the top reasons why blue collared labor is being phased out is not only due to outsourcing, but also from the installation of robotic workers (i.e. Amazon's warehouse infrastructure). One of the fundamentals of programming or software engineering is the ability to reuse code, modules, frameworks, you name it. With this level of automation already in place and still growing, there's absolutely zero need for this class of blue collared knowledge workers as you've described.