Their customers, if you think about it, are perhaps more likely to value what the domain stands for. Meanwhile the annual price is currently absolutely trivial versus the expenses of most organisations from higher GDP countries.
Some of their customers perhaps. If you go back and look at what companies were doing with domains 20 years ago most medium and large enterprises bought <company name>.com, .org, .net and some country code tld domain because that's what everyone recommended "in case someone cybersquatted". I think behaviour has stopped now there are hundreds of gTLDs available. Consequently .org is much less likely to sell to businesses, and will find it very difficult to grow.
Perhaps by some percentage of them are registered non-profits. However not the majority.