The Infrastructure Argument Against Infill

One common (if vague) argument against upzoning and infill development is that infrastructure in place X (wherever the proposed development is) will somehow be overwhelmed by more important.  When I see this argument I want to ask:

1.  What infastructure are you talking about?

2.  How is it currently inadequate in place X?

3.  If you don't want more people to live and work in place X where do you want them to live and work instead? 

4.  Do you really think the infrastructure there is any better than in place X? Why?  Can you prove it?