This is true. Perhaps the other thing some people are missing is that they're not expecting 100% compliance with this, as with other Covid measures. It's like the rules on face masks. In an ideal world everyone would have to wear a medical-grade mask in any public space, but that's just not going to happen and trying to make it so would probably be counterproductive, and since any face covering is a lot better than none the rules are framed so as to allow people to cover up with pretty much what they like.* Similarly, they're well aware that groups of more than six are going to continue meeting, but probably a lot less and not so much in public places, which will help to drive down transmission. There's a sensible degree of flexibility built into quite a few of the restrictions IMO.
*That's not to say the rules on masks are being enforced adequately: they just aren't. Shops and public transport providers, especially, should be much more aggressive about refusing service to people who won't mask up.