Babies who might have reflux, colic or wind because they are unable to maintain a deep latch at the breast/bottle. Constant or sporadic feeding, reflux, vomiting, spluttering, gulping and bobbing on and off when the milk ejection reflex (let down) is triggered or the bottle tipped (often still on the slowest flow regardless of baby's age) - because they can't organise and co-ordinate their sucking and breathing fast enough (oh so often diagnosed as "fast let down" - it's not, the mum has a perfectly normal speed let down) some that refuse the breast entirely, others barely letting it go! Sometimes baby only has one or two of these symptoms, others many, yet treating the symptoms is far more common than dealing with the cause.
Some are told as their baby can protrude their tongue, the tie is mild; others after someone has had a cursory look in baby's mouth - perhaps the only thing worse is the "there's no tie" (when there is) or "baby has a short tongue", but all can deter mums from getting timely, appropriate help.
The other BIG problem is that by simply having a quick peek in a baby's mouth - whilst you can often confirm if a tongue tie is significant, it's much harder to confirm insignificance. In order to do so you have to piece together the signs and symptoms, watch the baby at the breast/bottle, assess the baby's suck and what the tongue is actually doing whilst baby is feeding, and if there are significant indicators, a specialist who is competent lifting the tongue to complete the picture.
Because tongue tie isn't about how the tie itself looks, but about how it allows the tongue to function - looks can be deceptive. A tie can be like a super thin wire, or slightly wider and diaphanous - still appearing "tiny", yet if it is tightly holding the tongue, it matters not if it's super thin or a more chunky number. Furthermore a tie can look insignificant from the front, but when assessed properly, one can find the frenulum runs back down the tongue, getting thicker and causing significant restriction further back.
To feed effectively the tongue needs to not only be able to protrude, but also needs to be free to move laterally in a co-ordinated fashion, plus it needs to elevate and undulate ie a wave like motion. How can you confirm a tongue can do all those things with a glance?