This is so crazy. Companies benefit from OSS so they need to pay? Come on. Companies benefit from OSS because the core idea of most of these licenses is exactly this - everyone can benefit even without contributing back. Don’t like it? Think this is not fair? Don’t do OSS or pick a more restrictive license.

If a company pays for your work time not work products (many contracts work like this) they have the full right to expect that during this work time you do the work explicitly ordered by them. It’s not only the law - it’s common sense.

Unfortunately there are often questions of liability. What if you commit code that later becomes subject to litigation? It's more complicated than "we don't want to". (I'm fully supportive but when legal is involved you have to be able to justify the risk).