Re: "unique screw head types and gluing or soldering components"
New screw head designs: Electronics are getting smaller and thinner, so manufacturers want to use as little space for screws as possible. So they are using smaller screws and the head of the screw is made from thinner metal, existing screw heads don't work very well at these small sizes and with such thin metal on the head..
Glue: Makes construction simpler, allows the design to not need screw nuts thereby eliminating stress risers from the design of the body making the device more study and durable.
Soldering: The points you mentioned.