Especially if it’s going to be a small ROI for the IRS.
I know in tax planning for high net worth individuals and businesses there is often a question about how the penalty (downside of being found to owe more tax) relates to the upside of just not paying the tax. For matters that aren’t so clear or where the tax code can be interpreted many ways - it often comes down to the decision maker’s risk tolerance.
So it’s smart for the IRS to avoid cases where a hundred hour audit gets them another $2k vs litigating a $20m underpayment over a grey area.