The Shard has a hotel (Shangri La) with a separate entrance, and no security to get up to the 52nd floor Gong bar (as well as several other restaurants and bar from 30th floor and up)
Next door you need to go through a scanner to get up to the restaurants on the 31st and 32nd floor of the Shard.
Security in these buildings is very arbitrary. I can get that some of the more high profile places feel more of a need for security, and assume that anyone up to no good will perhaps not be the brightest of the bunch and/or will go for more symbolic targets, but still.
Right, the security is all theatre. My comparison is specifically to show that the security at Sky Garden (free) is not implemented to discourage free visitors when The View from The Shard charges lots of money and wants as many visitors as possible and has the same security.
I agree with that. Which tall buildings in London has security or not is really haphazard and absolutely correlates very little with fees.