The push-in terminals have now been widely used in Germany for about 30 years, they are more reliable than screw type terminals. Screws in sockets and junction boxes tend to loosen over time, this is usually caused by thermal stress on the connection. The best case is the connection becomes loose and starts to arc then over time the connection burns out and the connected circuit stops working. This is when people notice something's wrong. Worst case is the connection heats up due to higher contact resistance and catches fire.
Not long ago I fixed a circuit in my granddad's cellar that stopped working exactly for this reason.
I've seen loose screw connections in junction boxes more then once.
Another problem contributing to that effect is cold flow of the copper conductor under pressure.
Good push-in connectors (like the Wago type) do not suffer from these problems. I'd say they have proven to be superior to screw terminals.
Now even some 32A 3 phase CEE connectors use a push-in connection, no ferrules required.
I don't think we'll ever see the Brits abandon their clunky monstrosity of a plug. The weird ring mains configuration they used for decades forbids it
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A world plug and world voltage sounds good in theory but does anyone really think that's ever going to happen? I'd say we're about a 100 years too late now.