"Bhante" is not only for the Buddha. It can be used by laymen to address monks too.
For example, in Nandamātāsutta (AN7.53), Nandamātā addressed Venerable Sariputta Thera as "Bhante":
Ekamantaṁ nisinnaṁ kho nandamātaraṁ upāsikaṁ āyasmā sāriputto etadavoca: “ko pana te, nandamāte, bhikkhusaṅghassa abbhāgamanaṁ ārocesī”ti?
“Idhāhaṁ, bhante, rattiyā paccūsasamayaṁ paccuṭṭhāya pārāyanaṁ sarena bhāsitvā tuṇhī ahosiṁ. Atha kho, bhante, vessavaṇo mahārājā mama kathāpariyosānaṁ viditvā abbhānumodi: ‘sādhu, bhagini, sādhu, bhaginī’ti.
Translation:
Nanda’s Mother sat down to one side. Sāriputta said to her, “Nanda’s Mother, who told you that the Saṅgha of mendicants was about to arrive?”
“Sir, last night I rose at the crack of dawn and recited the verses of ‘The Way to the Far Shore’, and then I fell silent. Then the great king Vessavaṇa, knowing I had finished, applauded me, ‘Good, sister! Good, sister!’
