It is self serving to label a multi carrier business model as unethical just because they make it hard for you to compete.
Its like the Concorde having the best safety record and one crash turning it into the worst. (Hopefully you'll have landed when you read this)
Becoming a Dairy farmer is pretty easy and there are very low barriers to entry. It is so easy to get into that if they didn't fix the price of a gallon of milk no one would make any money!
Tomtom, most of the issues I have seen around this have come from small carriers looking for a foot hold. I never have to worry when I am working with an exclusive carrier when booking van freight that they are under insured. But we better know the carrier real well before we trust that they are not committing fraud with insurance levels. I don't want them to be certificate holders but additional insured.
Any carrier that understands the risks (and surprisingly there are many that don't) of allowing someone to be under insured and commits fraud in the process will not be in business for long. While I can believe that some recruiter may have been trying to meet numbers for a month I would be very surprised to see this happen at higher levels of any major companies. But I see marketing material from small companies promoting this practice.
Maybe this is something we should have Sylectus address?