As explained in the relevant Wikipedia page:
Following was written and planned to be as inexpensive to produce as possible
For the most part, Nolan filmed without professional film lighting equipment, largely employing available light. This was made easier by the decision to use 16 mm black and white film.
This was explained by Nolan in ...
Why wouldn't he accept it? He got a credit card as a gift to use for his own needs and he's already done other illegal stuff at that point and he wasn't really considering the moral or personal consequences of those things at all, let alone the possibility that Cobb had something more sinister in mind for him.
Let's look at Bill's situation. He is basically ...