Domestic ownership is probably more important than foreign in some cases. Due to tax treaties the IRS and CRA communicate pretty regularly for example and can get ownership structures as it's standard on all Canadian corp tax returns (schedule 50 for the nerds). It is a hassle and a real pain in the ass to do it, but it really only needs to be done once and then only when there actually is something that changes the structure.
Let's say I'm running a "consulting" firm in the DC region and I want to make sure that my "owners" don't get any scrutiny when they decide to run for office in the future, I would absolutely support this measure because I don't have to disclose the ownership of the company.