The downside to that, which I've read many people complain about, is that during those peak times, you simply can't get a cab. With a constrained supply and fixed pricing, demand outstrips supply and then you may or may not be lucky enough to get a ride. That's the whole reason they have surge pricing: to get more drivers out during those times to handle the load. Cab drivers have little incentive to bother driving during peak hours since they get paid the same.