Need some advice

My son is 3 and still hates having his hair washed and brushed. I’ve tried having him help, washing it with a cup, washing it with the shower hose, using a kids pitcher and using those hat things the make it where their face doesn’t get soaked. I’ve tried different soaps to see if what I was using was hurting his eyes. At this point I just let him scream and we get it done as quickly as we can. I feel terrible every time but his hair gets so gross.