ETFs are usually cheaper than mutual funds whether they are unit trust or investment trust. While an excellent manager of a mutual may beat the index which is tracked by an ETF, the long term difference may not be that big because the manager usually has his/her own investment style, for example growth or value, which comes and goes over the years while the index performance benefits from both styles as they rise one at a time. ETFs provide access to thematic areas of the matket, for example electrical cars, battery, hydrogen etc while there is no fund that is dedicated entirely to any of these themes.

I would say the issue with Vanguard ETFS is the cost of them, i.e VEVE is currently £88, so if you are a regular saver of say £250 a month, you are only going to be buying 2 Shares you will be left with £74 uninvested for the month, so the next month you need to tinker with the amount you invest, so it is not invest and forget. It is invest and tinker a bit with the amount the next month.

I have never understood why they don't split the shares to make easier for regular investors.

(This is unless you use a platform like InvestEngine or others that support split shares)