I think a bit of background is in order here. H4 EAD's are only issued for People with pending Greencard applications, that is for someone with an approved Greencard petition.(I-140). So, for some one from the countries you have described, there is no greencard wait times. Which means, a spouse on H4 visa would not have to wait-forever to get work authorization as the primary petition holder can quickly get their Greencard. Not the case for someone "Born" in countries like India, where the wait-times for Greencard is currently at a minimum 10 years and at a maximum 120 years. So, yes this really looks like it is being targeted against people born in a single country.
(I am going to assume you are genuinely curious and will answer sincerely. Also, this topic has enough easy to Google sources for my claims below that I am not bothering to cite them, primarily because I am on my phone. However I am happy to add them later if that becomes the only point of contention)
Actually there aren't (white people being affected). This primarily affects Indians and to a lesser extent, Chinese immigrants.
For every one else, if you are here on a H1, and your spouse wants to work, you apply for a green card and get it in about a year. Now you and your spouse can work (and NOT WORK without consequences) for the next 10 years, after which you have to renew your green card.
If you are from India, your green card queue is currently estimated to be 30-100 years long. This is because green cards have country of birth quotas that ignore the population of countries. During this wait time, your spouse cannot work unless they can find another employer to sponsor an independent H1B for them. Also, you have to renew your H1 every 3 years, and if you lose your job, you have less than a month to find a new one, else you have to leave the US.
The Obama administration started the H4 work permit for the above situation, for people whose spouses are stuck in an insanely long green card queue. The number of people actually on H4 work permits is a miniscule percentage of the US labor force, such that it is not going to change any economic dynamics. But it is a massive blow to the unfortunate spouses who rely on it.
At which point, the most likely logical explanation for this step is that the Trump administration thinks that it will please his primary voter base, and the actual distribution of the affected people suggest (even if it is hard to prove) that racism played a role.
