The technology is just means to an end. Would you be ok if security had a big wall with printed pictures of undesirables and kicked her out due to this?
Not so easy to enforce, because most ticketing systems don't require the name of every single attendee. Adding that requirement would be really really bad for the sales funnel, and also require tickets to be 100% non-transferable.
And much less disruptive to the target, because they get told in advance and don't drive and park and go in and plan only to get kicked out.