[goldstategop]

There are legitimate reasons for depositing less than 10,000 dollars.

The bank may be liable for not telling their client it had to file a SAR report.

She could recover damages.

[PAR35]

There are legitimate reasons for depositing less than 10,000 dollars.

Yes, but so "the bank avoids paperwork" isn't one of them. And, as she's found out, the bank didn't avoid paperwork.

[PAR35]

The bank may be liable for not telling their client it had to file a SAR report.

I don't think that banks are allowed to tell you whether or not they've filed a SAR on you. And there are protections for the bank. Here's an old PDF on the subject: http://www.fincen.gov/statutes_regs/guidance/pdf/advis35.pdf

[generally]

One obvious reason would be that your business makes less than 10,000 per day. I would expect that to be quite common with a small business.