There are stil some thing that you can do.

1. 跟他们说狗狗带回来就去打疫苗 - They were just trying to save money but do not know the consequence, so you can offer to pay for it and you bring the dog to the vet. Are you working? It is difficult to change them when they were brought up in an era that even kids did get any immunizations, never mind dogs. You seem to fail to understand why they acted that way.

2. 开车从不系安全带 - Tell them if they were found not using the seatbelts, they will be fined, also tell them if they ever get into an accident, then ICBC may not pay them for injuries. Will they get scared and the start to use them? 

The other way is to search the Internet and print in Chinese and let them read it on what is the consequence if they do not wear it. You told them but did not let them know what if they do not wear it - the consequence.

3. 一定要装烟雾报警器，嫌麻烦觉得没必要 - It costs about $35 or something, you just buy it and install it. Tell them the homeowner insurance requires it.

4. 花钱让他们去医院体检，骗我说体检了 They should be covered by MSA, right? If they do not really want to, then leave them alone. 

You will be a nice mom/dad and a very nice wife/husband one day.