[DAFU]

I can certainly see the need for intense scrutiny of your taxes as someone who is self-employed. The tax system is complicated and unforgiving and I can emphasize with anyone who is, or has had difficulties with the IRS.
For myself it's pretty easy to figure my deductions and come close to the correct number at the end of the year. I prefer to be on the positive side for various reasons and find the penalty to be negligible.
I also think some use the refund as discretionary income that may be difficulty justifying paycheck to paycheck. That might mean some may have some extra cigars on order at this time of year. But hey..................at least they're not being charged on a CC that might not be paid right away.