A lot of bigger companies also supported it because they were already giving their employees a lot of these benefits anyway and they had competitors who weren't. This enabled them to raise the cost of doing business for their competition without having to do anything on their own like cut the cost of their product to be more competitive. So they were Chamberlains of convenience.
The use of gov’t regulation as a strategic competitive weapon has long been popular but has become especially popular in recent years. Make donations to the candidate or party—get indirect help when a regulation appears that hurts your competition.