This is really interesting - as the basic worker regulations that Uber have tried to avoid catch up with them they could face these liabilities in all sorts of different markets. For non-UK readers, it's standard that all employers must contribue a minimum amount (recently raised to 3% of qualifying earnings) to a pension and by default employees contribute too. It's fortunate for Uber that this scheme is only relatively new (I think the reason this dates back to 2017 is that's the first year of mandatory employer contirbutions but I could be wrong), but this is a big liability and just 1 more way that Uber was using regulatory arbitrage to out-compete local businesses.