It's relevent because if it costs more to employ staff (inefficient or not) than using technology instead, why would they continue to employ staff?
Reduce the amount of jobs available to the low earners because they are replaced by technology and what do they do for an income? live of benefits...
So sack the inefficient workers? rather than pay them a little more? or seek solutions which use technology rather than staff (self service tills in supermarkets) - is that good for low income workers?
Putting up the minimum wage puts up costs to companies, (everything from food to transport and everything in between which employs staff) which pass on these extra costs to customers meaning often those in reciept of an increase are in fact no better off than before but it makes good headlines...