This really depends on the country you live in.
Not really. There are two aspects to this problem: one is how people assign arbitrary and meaningless titles to themselves, and another is regulatory requirements by jurisdictions to be able to legally assume a role.
I can call myself senior dubstep engineer, and that's perfectly fine. I can't call myself a civil engineer and sign off on a construction project or a permit. No one cares if I'm actually a senior dubstep engineer or if I'm junior at best. In the meantime, you will get in trouble if you try to sign off on a construction project, no matter of how stubborn you are with regards to calling yourself an engineer.