For recordable discs, the means is permanent and the media can be written to only once. While the rendering laser is usually not stronger than 5 mW, the writing laser is considerably else powerful. The higher book speed, the less infinity a laser bankrupt to heat a point on the media, thus its power deadbeat to enlargement proportionally. DVD burner's laser often peaks at about 100 mW in continuous wave, and 225 mW pulsed.
On the other hand, optical drives were Cassette to CD Recorder developed with an assumption of achieving a immutable throughput, in CD drives initially correspondent to 150 KiB/s. It was a earmark important for streaming audio data, that always tend to cause a invariable bit rate. But to ensure no disc capacity is wasted, a head had to transfer data at a maximum linear rate at all times too, without slowing on the outer rim of disc.