There are some merits to this idea, but there's a major flaw. It's kind of like tax havens. If you have two countries with different tax rates, all else being equal, a multinational will set up HQ in the lower tax county. Likewise, for pharmaceuticals, the company will pick the country that has the lowest barrier to entry and then sell to both.

While within a country a given barrier may be too high or low, it will probably be somewhat randomly too high or low around some appropriate level of safety. With the multi-country scheme, the bias will be towards too low on nearly every drug.