Well they did
You interpreted DTs remarks to indicate that Mexico would as DT said..."write a check"
But even politico agreed they would pay indirectly
Read their article and whilst they acknowledge the trade deals DT organised
would lead to income to the US...given their strong tilt to the left they tried as best they could to say none of funds would be DIRECTLY sent to pay for the wall
Its almost as if those really smart folks never heard of the term "fungible"...ya know how funds to an organisation et al are "fungible"
Hmmmm
Fact check: Mexico will 'indirectly' pay for a border wall through the new trade deal - POLITICO