Its pretty much impossible for a single engineer to destroy a tank or IFV on their own. 3 hits to the side with an RPG will not kill a tank. Plus, half the tanks I run into have a full F1-racing style squad of engineers repairing it the entire time. In the beta I was able to kill tanks solo if I managed to get all three shots into the back of a Tank or IFV.
Also, theres literally equipment you can put on your vehicle that scans for mines in the area and pings them. Not to mention they stick out like a sore thumb on their own without the equipment.