The must be somebody somewhere that can make a cheap simple bike that doesn't weigh a tonne - look at the number of choppers and burners still going strong (i know they weren't light, maybe sacrifice a touch of that duarbility)
I do often wonder how come a for instance an XT mech is maybe 15% lighter than it's 90's equivalent - but a TY25 / SIS mech is still all pressed steel and just a heavy. Filter down would seem to be a myth.
When it comes to cheap bikes steel must be cheaper than thinking.
This is probably more than strong enough = add more steel
The alloy one is 5p more = add more steel
this plastic is awfully flimsy and brittle = add more steel
Nexus hub with chain cover
Not really a "cheap" bike then is it - although probably still vastly over built for a crash it would never encounter