Colonisation is OVER

European countries have colonised and used Africa's land and people for some time, from the Portuguese to the British, and yet we've stopped trying to "take over" African countries.  Contemporary times seem to be focused on reparations or dealing with the consequences of colonisation, instead of continued use and exploitation of the land.  Why?  Is the land that shitty that agriculture won't continue to thrive?  Are the people that lazy that they can't force everyone to work towards industrialising civilization? 

Also, how can we terraform dry and arid land into fertile soil in order to grow crops?  This applies to Africa, the middle east, and parts of asia.  There is so much unused land, so why can't it be infused with nutrients, fertilizer, nitrates, etc.

Why do European countries seem so uninterested in developing and using Africa, compared to the past few centuries?  Have they all given up?  There are still wealthy industries run by wealthy individuals, such as diamond mines and rubber, but as a whole no one seems to be interested in making Africa a modern civilization with great industrial and agricultural output. 

Something like Brazil, for an agricultural example.