Most landlords require your business to have liability insurance of at least $2 million, and often up to $5 million these days. Landlords do check on this, requiring a confirmation from your insurance company every year.
If you are a contractor, similar liability insurance is usually a requirement in contracts as well. It's a standard boilerplate term in all government contracts even if it would appear not to be necessary for the goods or services you are supplying. However governments don't usually check since they often have thousands of pages of obscure requirements that are mostly not applicable (e.g. accessibility of bathrooms in your offices), and any that might be important get lost and ignored in the general clutter.
I don't have much input other then the fact that I had to have insurance when I was doing IT contracting, it was a requirement but I was never asked for proof, so I never bothered with it. I did price it out and it was something like 3k for professional liability insurance, not sure if that's what you are looking for or more. Either way, the process for applying sucked, was asked so many questions about type of consulting you do, if you recommend things or implement them etc etc, it was very detailed. I went through the process and was going to execute on if it ever asked, but I was never asked for 2 years so never bothered, and then got a full time at the company so never needed it, work here to this day.