Many possible explanations. One of the most common ones is cash flow. If you're somewhat at break-even, there just isn't any $1,500 around, but there are enough jobs to pay $320 a week, and do that every week. (This is by the way the same reason poor people often make "stupid" decisions)
This is the most common case for smaller companies - it's all hand-to-mouth, and you barely squeak into profitability, so you minimize one-time expenses that shorten your runway. (What we around here like to call "Ramen profitable")
There's also the fact that even with a tripod, you probably want somebody around - assuming they use high-end movie gear, a camera runs between $100k and $500k. Spending $10k a year on somebody who catches it in case of accident makes sense.
I'm sure there are other explanations. I'm sure there are places that make stupid decisions, too :)