The Bible uses the term 'pastor' along with apostles, prophets, evangelists and teachers.
Ephesians 4 Authorized (King James) Version (AKJV)
11 And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers; 12 for the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: 13 till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ:
All of these of course should be Godly people but there are no definite rules laid down for their conduct here.
But along with these people doing these ministries there are also elders and deacons that have been ordained to fulfill their ministries in the churches. There are definite rules laid down for the behaviour and conduct of the elders and deacons.
1 Timothy 3 Authorized (King James) Version (AKJV)
1 This is a true saying, If a man desire the office of a bishop, he desireth a good work. 2 A bishop then must be blameless, the husband of one wife, vigilant, sober, of good behaviour, given to hospitality, apt to teach; 3 not given to wine, no striker, not greedy of filthy lucre; but patient, not a brawler, not covetous; 4 one that ruleth well his own house, having his children in subjection with all gravity; 5 (for if a man know not how to rule his own house, how shall he take care of the church of God?) 6 Not a novice, lest being lifted up with pride he fall into the condemnation of the devil. 7 Moreover he must have a good report of them which are without; lest he fall into reproach and the snare of the devil.
8 Likewise must the deacons be grave, not doubletongued, not given to much wine, not greedy of filthy lucre; 9 holding the mystery of the faith in a pure conscience. 10 And let these also first be proved; then let them use the office of a deacon, being found blameless. 11 Even so must their wives be grave, not slanderers, sober, faithful in all things. 12 Let the deacons be the husbands of one wife, ruling their children and their own houses well. 13 For they that have used the office of a deacon well purchase to themselves a good degree, and great boldness in the faith which is in Christ Jesus.
Those in the "churches" today who call themselves "pastors" don't seem to even know that they are not pastors but are rather holding the position of being an elder or bishop in a church and doing it very poorly at that. If they understood scripture they would never go around calling themselves "pastors".
Maybe they don't like being referred to as elders because then even the "luke warms" in their congregations might notice there are definite rules laid down for an elder or bishop and they know that they are definitely outside the bounds of those rules.