FM is superior to DAB for the following reasons:
1) From the point of view of the broadcaster and the listener, DAB is more expensive to run than FM. It consumes considerably more electricity.
2) Due to point 1, running DAB from batteries is particularly expensive. This effectively stops many people from using DAB as a truly portable device.
3) Sound quality on DAB can be reasonable compared to a very cheap FM receiver, but comparing like for like prices, FM tends to sound much better. Where reception is marginal, voices carried on FM can still be understood. On DAB, with poor reception, much worse distortion of the signal can occur including drop-outs to complete silence.
4) The DAB standard is based on 30 year old technology. It has been superseded by many other standards. Nearly all other countries which are adopting digital radio are opting for one of the more modern standards. This will mean that people using DAB in car entertainment will be unable to receive radio if driving their cars abroad. It will also drive up the price of DAB.
5) There is a significant time delay in the encoding and decoding of the DAB signal. This delay will vary between different receivers so it is impossible to compensate for. This means that the time signal used on the radio will be useless.
6) Due to the frequency of the DAB signal, it can be blocked by metal used in the construction of modern buildings (Faraday Cage effect). The FM signal is much less susceptible to this.
7) Most families have several FM radios: kitchen, radio alarm, car radio, hifi etc. Replacing all of these with DAB will result in huge expense to the listener. It will also result in hundreds of millions of FM sets ending up in land fill.