The LB/ESC has a microcontroller, which is a very primitive, slow computer, but it is digital. By the looks of the PCB, it looks like a 4 Bit CPU (same as would be found in calculators). It really doesn’t do that much, which, only taking in vacuum, RPM, temperature, and throttke position, and only outputs an ignition pulse. It probably can’t output diagnostic codes.
Modern automotive computers are mostly 32 bit, and must have 50-100X the RAM and Flash storage (equivalent to the ROM/PROM in the above circuit board). For things like adative cruise control, they are probably adding a DSP chip.
All signals from the various sensors are analog. The real world is analog in that it doesn’t change in steps (think temerature, air pressuer, coolant temerature, etc.). The analog signal is converted to digital (by A/D convertirs) so that it can be input into the digital CPU and the software can work with it (same is true for the LB/ESC computer).
Analog computers can be made, and they are in use. But the can not be programmed, and they are for very specific uses, and are not generally used.