You are comparing apples and oranges here, these resistors such as the L&N 42xx series are made with Manganin and are soldered, PWW resistors such as I make are made with Evanohm alloys which are not solder-able and must be welded. It is not the 'crude' construction as much as the processes used to make them stable.
These resistors require entirely different methods to produce the end result, using the same methods on Evanohm resistors wouldn't even bother them. Some of the Soviet style resistors similar to the L&Ns were actually made with a relatively thick sheet of Manganin with heavy copper leads soldered to the sheet. Others such as L&N used heavy gauge wire instead with smaller gauge wire being used for higher values. On the whole, the techniques were not that different between the Manganin type standards. None the less, it does take considerable care and handling to produce such stable Manganin resistors, it isn't an off-the-shelf type of thing. Manganin does remain very sensitive to handling and its environment unlike the Evanohm standards such as the SR-104.