$176 Billion Un-refunded Income Taxes

Today, the news wires were alive with a report the IRS has $176 billion in tax refunds coming to people that have not filed income tax forms to reclaim money deducted from their paychecks by their employers for the IRS.  They have until midnight tomorrow night to reclaim their money.  Why would someone not file an income tax form (Form 1040) to reclaim excess taxes deducted from their income?  The news reports, probably based on IRS sources, have claimed it is mostly students and part time workers that have no idea they have money refunds coming to them.  What is ignored and would be most interesting to know is how many of these people are illegal immigrants gainfully employed under assumed social security numbers that do not want to file tax forms for fear they will be found out and deported?

And, we have the most transparent government of all times?