for tower crane, they use mobile crane to fix tower crane at bottom. then the tower crane will keep add the mast on itself to increase its height. can found those video on youtube in fact.

for backhoe, normal construction work don't need it at top level. but of course got exception got certain case. demolition of building usually need backhoe on the of building if it were to demolish 1 by 1. and yes, they use mobile crane to lift up the backhoe to the building. u will surprise that there were actually 500tonne mobile crane available for rent. daily rental could be abt RM50k a day.