Unless you have lost a dear one in an RTA, I don't believe you have the right to comment and you definitely should not remove it.
We all have the right to our opinions. If it was on my property, I'd leave for a while, say 3-6 months, but I'd then clear it all away.
And why is is just for those lost in an RTA? I lost an aunt, she died in hospital. People would rightly object if I were to constantly place flowers to her in the room she died, and this is no different to me.
I lost my mum late last year, and her ashes have been scattered in a lovely corner of the crematorium. A place where I can go to remember her, without impacting on someone else.
The roadside shrines distract drivers, and the cellophane and plastic tat is harmful to the environment and animals. A simple plant in the area, fine, but the rest of it, no.
There's one on the commute to work. It's been there for at least 30 years. Has now reduced to a simple cross, but that's only recently. About 5 years ago, when the plastic was still there, we had a really windy night and driving to work the next day there was loads of the stuff littering the road, and yes, creating a hazard. It's also on a road with no pavement or easy way to reach the site, thereby creating another hazard of pedestrians.