Actually it’s not 1s and 0s. It’s not 1s and 0s until the data gets to the A to D converter. The laser is simply reading ON and OFF depending on whether the laser beam is hitting a pit or land. Actually the laser reading process is an analog process, not digital. Also, the length of the lands, which are variable, helps determine what the actually digital data is.
There are several problems that make the reading of the “data” on the CD imperfect. One is wobbling of the CD due to out of round condition, various types of vibration and/or not being absolutely level during play. Another is background scattered laser light that makes its way into the photodetector. The photodetector is kinda stupid and can’t tell the difference. Yes, I know what you’re thinking, “But the Reed Solomon Error program is supposed to take care of all that.”