1. It's incredibly illegal for an agent of the government to do this, and people get fired and prosecuted for this.
2. It is possible to couch this in a revolving-door sort of arrangement - once the agent stops working for the government, they get a cushy job at the vendor. In theory, the vendor has no reason to hold up their end of the bargain, once the person they are bribing is out of office. In practice, that person can then leverage their government connections to smooth out future business deals... Which in itself is not illegal, and is convenient cover for the job.
1. It's incredibly illegal for an agent of the government to do this, and people get fired and prosecuted for this.
2. It is possible to couch this in a revolving-door sort of arrangement - once the agent stops working for the government, they get a cushy job at the vendor. In theory, the vendor has no reason to hold up their end of the bargain, once the person they are bribing is out of office. In practice, that person can then leverage their government connections to smooth out future business deals... Which in itself is not illegal, and is convenient cover for the job.