The thing is, United and Liverpool sell their tickets differently to us. United operate a ballot system so everyone who wants a ticket has to apply in advance and fans then get told if they were successful or not, whereas we operate a points drop system so not everyone qualifies for a ticket straight away. In fact, it was only this morning - 5 days after they first went on sale - that all season ticket holders were eligible to buy, so it's not even gone on sale to non season ticket holders yet. Liverpool also have a ballot system but theirs isn't just one ballot like United and instead is several different ballots. However, for an FA Cup semi final it would go way beyond season ticket holders as the allocation is 34,000 and they only have something like 26,000 ST holders.