That's a more interesting point than your original one. I think part of it is underinvestment but companies need incentives to invest. Windfall taxes for example are a disincentive. Companies are better at investing than government because they better understand what their industry needs. To invest, they need to keep more of their money. They also need to be a bit leaner - clearing out a lot of unproductive middle management (same is true for schools and hospitals) - or using consultancy firms that do little (media advisers, PR, advertising people, and other creatives plus all the diversity industry).
Businesses used to do all that in house and as a much lower portion of the investments they made. Or even when they bought is in, it was a much simpler product (art for newspaper ad, etc., not some creative's 'vision'). Health and safety, though much maligned, is however a part of middle management worth keeping. It is easy to forget how many people suffered industrial accidents.
I run a business: my biggest barrier to growth is all the various things I have to sign up to, to export - instead of saying small businesses of less than 100K turn-over can just pay a flat fee to contribute to whatever bit of social engineering is current (VAT in country of sale, green packaging levies etc - nothing to do with Brexit which in my industry has been no problem) they want me to pay lots of small sums with lots of attached paperwork - keeping track of every bit of packing I use and its content for example - I don't have time, should I employ someone? How is that productive? I like Truss' idea that government should do less and do it better. I'd give her a chance.
Investing in broadband, energy infrastructure, high tech batteries, transport and ports is needed. The Tories are committed to two of those already. I'd like to see what they do with the railways/smart motorways, etc. And the problems of lots of electric cars when when so many people live in terraced houses of flats. And problem of increased plastic pollution from heavier electric cars (plastic particles from tyres/roads/road paint is huge generator of plastic micro waste in the sea).
And btw just because people don't agree with you, does not mean they do not understand economics.