List of ways to come up with business ideas

I know everybody says "scratch your own itch", but there are other ways to spot opportunities. I've collected some ways to come up with business ideas. Some are generic, others are more specific.

What are your heuristics/frameworks to find business ideas?

Here is my list:

Browse Upwork jobs. Find tasks that are regularly posted. Can you build a service that makes this task more efficient or even automated?
Look for market inefficiencies: Not efficient in price (big price differences). Not efficient in time/effort.
Look for any mundane/repetitive tasks in offline industries. Can you offer an automated solution and save them time?
Look for value chains where you can remove one or more middlemen, and improve one of these attributes: price (reduce it), quality (improve it).
Look for companies that use several other companies to develop their product. Why do they outsource? Can you do it in-house? And what advantage would you have?
Look for products/services with too many options, but where the majority of customers buy the same thing every time. Provide a one step solution that offers just that.
Look for products that are unreasonably expensive. Look for businesses with unreasonable margin/profits.
Find an offline industry where it is hard to find information about it. Or where it is hard to acquire X product or Y service. Provide the information/service to make it easier.
Pick an industry and interview a person in that industry to tell you their top problems they experience daily.
What services/products do rich people have that poor people don’t?