You are right, casinos won't just give every account that goes inactive for some time a bonus to get them to be active again, if such be the case, alot of gamblers will purposely leave their account to enter inactive status just to gain free money from the casino from time to time, or some gamblers who would still want to be gambling even while chasing for this bonus will be driven into creating multiple accounts and using fake documents to get the account verified, and he or she will use the alt account to farm the inactive bonus while he gambles everyday from his main account.

My account on betfury and two other casinos have been inactive for over a year now, ive never recieved any email from any of this casino calling my attention to any prepared bonus to get me to be active with my account again lol.