There are laws against age, race, and other discrimination in employment. But it still happens, and in some industries in widespread.
Greed finds a way. Your point is moot.
While adverse selection is undeniably a tricky problem, the underlying raison d'etre is pooled risk, to help individuals and families mitigate catastrophic losses. Maybe you're all right with the prospect of future analyses condemning to uninsurability folks with rare combinations of alleles that turn out to be strongly deleterious. To me, this seems like breaking the regulated semi-statis between insurers and insureds, and like breaking the social contract more generally.
The whole system is going to have to adapt to more information on individuals being available.
This might or might not be an issue now (regardless of the place of residence), but laws can always be changed. And societies can always develop to be more totalitarist, even up to extremes, and it is not like the collected data just vanishes when things start to slide. (Case in point: IBM's Hollerith machines and population records)
I was very curious about 23andme and really wanted to try it. After some due diligence I concluded it is not worth it because of privacy and other implications going forward. It is not what they do today, since they don't hide the obvious sharing and datamining, so if one joins them it is through informed consent. My concern was rather what kind of systems and policies they enable eventually in the future, after the information gets sold/shared enough times to anyone who can pay enough. At this point there is no control anymore in how (and by whom) the data gets used.
Cue adverse selection. They might not be allowed to collect genetic data, but nothing stops patients from doing their own sequencing, and shop for healthcare plans depending on their predispositions, thus drastically affecting healthcare profitability.
This is not a pervasive problem yet because the tests are pretty crappy and very few people bother, but on the long run, I bet your "level playing field" hypothesis will be debated.
How about displaying recruitment ads to people with lactose tolerance gene, effectively excluding most of worlds non-white population?
> It shall be an unlawful employment practice for an employer-- (1) to fail or refuse to hire, or to discharge, any employee, or otherwise to discriminate against any employee with respect to the compensation, terms, conditions, or privileges of employment of the employee, because of genetic information with respect to the employee;
No job advertising protection there
NJ (LAD):
> It shall be an unlawful employment practice, or, as the case may be, an unlawful discrimination: a.For an employer, because of [..], genetic information, [..] to refuse to hire or employ or to bar or to discharge or require to retire, unless justified by lawful considerations other than age, from employment such individual or to discriminate against such individual in compensation or in terms, conditions or privileges of employment;
Nope, nothing there either about recruitment ads..
https://www.eeoc.gov/laws/statutes/gina.cfm