Lightning Network is currently starting to build up, it has recently passed 2 Million dollars in capacity, but its still far from being perfect, there’s currently very little ways of assessing how much fees a payer will pay, although its currently mostly a negligible value, it may not be in the future.
A use case of the Payee paying the fees of the transaction is used in almost every exchange platform, because on the main blockchain you can assess the current average fees and even figure out how much, on average, it will take your payment to be accepted by the network if you sent it with a definite amount, this currently does not exist in Lightning.
If the payee pays the fees the payer can route the payment towards complicit nodes that charge way higher fees than average.