Not necessarily in the literal sense, though that comes into it, too. It's knowing that fine line between encouraging independence, and making sure that they live long enough to enjoy the fruits of that independence. But, if they are walking rather than in a stroller, you can start talking to them about how to cross the road. They won't take it in the first time, but if you make a habit of talking about it, every time you cross a road, by the time they are old enough to think about the process, what you are saying will be engrained in their memories. And they are never too young to hear you say that it's very dangerous to run around near cars.
Every day is a challenge for a toddler.
Their little minds are constantly full of wonderful, exciting plans and thoughts, many of which don't survive the transition to the real work of toddler skills and abilities. This is one of the main causes of tantrums - frustration at not being able to put into practice the notions that they can think up. Encouraging a gradual growth of independence, of acquiring skills and putting them into practice, is essential for the proper development of a child. A two year old is neither a baby nor a pre-schooler, and it's always hard to know when to baby them and when to treat them as though they are growing up. Dummies and bottles have dental implications in the long run, so their use probably should not be encouraged in the toddler.