Because the cost of renewables is falsified, installation of renewables causes power crises. Renewables are installed. The cost of renewables is hidden in some other part of the system, renewables continue to be installed, that part of the system does not get increased funding, collapses, blackouts and brownouts ensue. Fixing the blackouts and brownouts costs money, the cost of electricity then rises to reflect the actual cost of renewables that no one will admit.
The cost of renewables is assessed without regard for the fact that renewables are intermittent and unpredictable. Sometimes the sun shines, some times it does not, sometimes the wind blows, sometimes it does not, sometimes it blows too hard and the windmills must shut down. This creates a burden on the grid, and the need for backup power, and this backup power and grid load is not costed or funded
So the overburdened grid shuts down, and you get blackouts, or there just is not enough power, and you get brownouts.
Eventually industry threatens to up and leave for lack of predictable power, and then, and only then, only after major threats from major industries, the additional generating capacity and grid capacity is built – and people have to pay for it. And then, and only then, the true cost of renewables becomes apparent.
Generating electricity costs very little. What is expensive is generating it when it is needed, and not when it is not needed, and transporting it from where it is generated to where it is used.
The rational way to charge for electricity would be like internet – charge by the size of the pipeline, not how much goes through it. Most of the cost of household electricity is the grid and power stations idling for times of peak demands.
The trouble with wind and solar is that sometimes the wind blows, and sometimes it does not, and sometimes the sun shines, and some times it does not. So it puts an unreasonable load on the grid and requires some kind other power source for times people want power, but the sun is not shining and the wind stops blowing.
If you have solar power on your roof, then when you feed excess power back into the grid it costs the power company money, because they have to have the extra grid capability to support unpredictable power being fed back into the grid at inconvenient times.
Hydroelectric is OK, provided one has a decent sized dam behind it, so that one can run water through the turbines when one needs power, and not run water through the turbines when one does not. It is the dam that is expensive, and the dam that makes hydroelectric power useful. Without a large enough dam, it is as useless and expensive as wind and solar.
If we had a cheap and effective means of storing power, then wind and solar would be great, and every household and every business would cheerfully go off grid and use solar for everything. High temperature batteries relying on molten sodium, molten salt, and beta alumina membranes are promising, but they are not yet economical in sizes small enough for household use, or even use by ordinary businesses.
The only cheap and effective means for storing power is pumped hydro. You need two large dams close together, one much higher than the other, and when the sun shines you pump water uphill, and when it is dark you run water downhill through the turbines. If you have rivers suitable for pumped hydro, then wind and solar is pretty reasonable. It is costlier than carbon and nuclear, but compared to the cost of the grid, not enough to make a huge difference.
Norway uses hydro, and hydro works fine. Austria uses hydro and pumped hydro. Portugal uses pumped hydro, and for them, wind and solar works fine. But most of the EU just does not have enough suitable dams for pumped hydro. And for them, renewable power sources are very expensive.
I took a list of EU countries that use widely varying amounts of renewable electrical power sources, leaving out Norway, Portugal, and Austria because of hydro and pumped hydro.
The cost of electricity in the remaining countries is, to a good approximation, proportional to the proportion that is generated renewably. Extrapolating to 100% renewable, it would cost 55 cents per kilowatt hour, extrapolating to 0% renewable, it would cost about 10 cents per kilowatt hour.