I haven't seen a transformer power supply on any of the new phones or tablets, or on any electronic device for a very long time. Most of them use switching circuitry to achieve the right amount of current and voltage. Once the job of charging is finished, they switch off.
I tend to agree with this. The chargers that I see these days for electronic devices tend to be "universal" chargers (100-240V, 50-60Hz), which is a clear indication that it is a switching power supply rather than transformer-based. Some, like those on Apple laptops, even come with detachable plugs so you can just snap on the plug used in your current location.
Generally, the quality of the power from these switching power supplies is much better. Using circuitry to regulate power is much better than leaving it to a transformer, which is basically "garbage in, garbage out."
