In the mechanical era when watches were assembled from custom made parts. prices were very high/ Eventually mass production brought prices down to the point where almost everyone on the planet can afford one.
There has to be a dozen screw heads out there. Each has advantages and disadvantages. It has forced tool sets to be more complex as repair services struggle to keep machines in service. Several sizes of screwdrivers are needed.
M.2 and M.3 bolts are available in several standard lengths. M.2 is the screw that secures the SSD while M.3 are the type used to secure the floppy disk and DVD drive. SATA SSD also use M.3 screws.
6-32 screws are used largely with the peripheral cards, mounting the motherboard and securing the PSU etc. 6-32 is by far the most widely used with desktop machines.
Disassembling the Lenovo machines for service found large numbers of M.2 screws of varying length. The disassembly was needed to replaced the WiFi card and to install mSATA SSD units.
Some Dell power supplies have unorthodox power connectors which suggest that their machines have poor repairability. Toshiba is in the same boat with repairability.
Laptop power cables are all over the dial. The industry has settled on 19V which is enough for regulators to be efficient. Most universal replacement power supplies are equipped with 12 connectors.
Soft metal has been a problem with some repairs, it seems that the cheapest screws need to be replaced with better quality ones on a regular basis.