[gh02t]

Scopes and digitizers are actually extremely demanding in terms of throughput, plus they do a lot of specialized processing on the samples. Even mid-range models are using top-grade FPGAs and custom ASICs. Keysight's mid-range scope is capable of 5 gigasamples per second at 8 bit sample depth on 4 channels, that's 20 GB/s of data that needs to be processed, [soft] real time.

Regarding cost, these are expensive, complicated instruments. A bottom of the barrel oscilloscope costs $300 and professional grade units are more like $2-3000. The top grade ones can cost half a million dollars ( https://www.keysight.com/en/pcx-x205212/infiniium-z-series-o... ).