MT4/5 - trading on every tick

Why can't MT4 trade on every tick, it could assess conditions on every tick, so why is it only able to trade on the first tick of each candle. Does Mt5 have the same issue or has it been fixed. 90% of EA's would be more profitable if it were possible to trade after entry/exit conditions were met for so many tics.

You are wrong, wrong, wrong. Perhaps the EAs you have looked worked that way, but that is because the programmer chose to code them that way. Usually it is done for a very good reason - the open bar repaints. Once it closes it doesn't. To do as you suggest would result in some trade entries that can't be explained on an historical chart. Whether the trades would be more profitable is open to speculation. 90% is your opinion, but I doubt if that figure can be verified.

When using a EMA cross system an EA that traded as soon as the EMA's crossed and remained crossed for 5 ticks would be way more profitable than if it waited till the candle closed. I've been using a universal EMA cross which works the way it was programmed and has a decent w/l ratio but the wins could be bigger and the losses could be smaller if the EA could trade as soon as the trade conditions are met for 5 ticks. Could it be modified to work that way?
More pips are more important than being able to explain every single trade.

Modifying it to take a cross immediately can be done as you describe. Whether it would be more profitable is unknown and very difficult to confirm without doing extensive side by side comparisons. I haven't heard of anybody doing this and in fact I think this is the first time it has been suggested. If you have a reference or link that discusses this, I and others would be interested. One thing you have to consider is that MT4 strategy tester doesn't use true tick data, so that needs to be a consideration.

I figured that if it could be done it would need to be forward tested on a demo account. I don't know why nobody ever thought of it before . I've seen discussions where the problem was pointed out but nobody ever suggested that it would be possible to program an EA to trade before the first tick of the next candle.
Every EA I've ever seen looks for the entry conditions then trades on the next candle which could be 20-50 pips after the entry conditions are met.
Know any programmers who could make the modifications?

I have also seen many instances where the entry conditions are met and within a few ticks, the price heads in the opposite direction. Its very difficult to say whether the gains would make up for the losses, which is why it would have to be verified.

The coder who wrote the original code should be contacted. For someone else, it is not an easy task.