A lot of absinthe is bogus. Much of the stuff marketed as "really real, we swear" has thujone but at very low levels, ~10mg/L or even down to 2mg/L. That is basically alcohol+herbs. It looks like the site you linked is offering stuff of that caliber. If you look around, you should be able to find 35mg/L, which is almost--but not quite--like the old days. Try
here to start (though I've never used this site and can't vouch for it).
Good absinthe should be obtainable as laws have recently been relaxed. Keep looking.