I wish I could answer all use belt positioning boosters with nice SIP but that's not true. There is a trend among parents to turn their kids forward facing earlier than before and also to use booster cushions more often. I see many kids at school using these which IMHO should be in a HBB. Nowadays you can't separate cushion from the back, this is an effort to increase safety even further.
I've had explained by people who know that most important thing with booster is to place the seat belt in a good position across chest of a child. Most cushions do a good job of this. A HBB (or harnessed seat) with good SIP looks great but does not provide much extra safety in a real life crash due to children's head often being in fron of SIP at moment of impact. This is often caused by breaking by driver but even without breaking, a childs head is often not well protected by SIP.
This applies both to forward facing harnessed seats and HBB. It does not apply to rear facing seats since child is then pushed further into seat and becomes more protected by these forces. Another reason for rear facing way longer than 12/20
I would say there are not many crappy boosters around but quite a few are only using booster cushions for their 5 year old. Fortunate thing is that many kids are not going into these cushions at ages like 2 or 3 years of age. It does happen but it's uncommon.
To get a feel for what's offered you can take a look a the Swedish Britax selection
here
Despite having great car seat safety our law is very lax and fines are not that high. Like eferywhere else it's up to parents to keep kids safe. I think most are doing a good job but despite low number of fatalities and injuries there is lots of room for improvement IMHO.:twocents: